Should I just throw out everything I know?
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I have brought my Rapid (15/10) rating from 550 to 859 and feel pretty good about my improvement, However I realize that 859 is barely scratching the rank of beginner. Are you expert players playing a totally different game?
Should I just keep doing what I am doing or adopt a book or specific methodology and study that? Play computer (To me level 6 is impossible), do puzzles, study opening strategy? Help!
I have played over 1250 games in the last 6 weeks.....ya I'm obsessed.
Study endgames, it teaches you how your pieces move and work best together. Good study pattern is endgame, middle, opening and repeat. But end games are what helped me most.
"Are you expert players playing a totally different game? "
I'm no expert but in some sense, the answer to this is yes. Or really, it isn't the game that is different but the way they think about it. Lower rated players see a forest of moves and have little clue which ones are good or bad. As you get better, some of those moves get to be just obviously wrong, and as a result, you can spend your time considering a much smaller set of possible moves with a much better chance of selecting the best one.
Play, analyze your games, read good books actively, do tactics, study endgames appropriate for your level, play over games from players much better than your, etc.
We don’t know what you know to decide whether you should throw it out 
In all seriousness if you’ve not been playing that long, your progress sounds totally respectable.
Study endgames and tactics. already been said I know.
Also, play over dozens of classic master games. Not current games - they are too complicated and dynamic. Get a book like "The most instructive games of chess ever played" by Chernev as one good example. Dont get too hung up on the variations. Just play over the games and read the notes (but again dont get caught up looking at a forest of variations). I would probably not spend more than 10 minutes going over the whole game.
This suggestion may puzzle you. But what starts to happen is your brain starts to begin the process of pattern recognition. The more you do this, the more patterns and ideas you will become familiar with and you will see your rating rise.
You will start to learn about pawn structures, and outposts, open files, half open files, minority attacks, etc. etc.
Trust me, it will work. but you have to spend some time doing these things and not just playing tons of blitz games. that by itself WILL NOT help you improve. The problem with that is that you don't know what you don't know and you typically won't learn it by just endlessly repeating the same mistakes.
Good Luck!
Wow! Thank you all so much for your thoughtful recommendations and wisdom! I have been communicated to analyzing my games and seeing the turning points and blunders that decided the outcomes. I will put your advice to good use! I especially like the point about not knowing what you don't know until you get more experience. That makes total sense.
If you started as a raw beginner, then your rating progress seems quite decent. Unless you become a Grandmaster, it will always seem as if the people a couple of levels above you are playing a different game. I had the opportunity to analyze a game with an IM recently, and his speed of calculation and deep theoretical knowledge just blew me away. Then he told me that about six months earlier, he had played a game with GM Wang Hao (FIDE rating 2714), and came away feeling that Wang Hao was playing an entirely different game at an entirely different level! So it goes
tactics
tactics
tactics
Yes, we are playing a totally different game to you. I just looked at the last game you lost against a 1000 rated player. Your opening was weak and didn't do enough to control the centre of the board, you sacrificed a knight for no reason, and you had an amazing attack going that should've won you the game, but you didn't have the tactical skills necessary to follow it through:
Try this, it works.
1) Choose a single opening for each colour. For black, choose an opening that can be played against almost anything.
2) Search for the opening on Youtube and watch every video available on it, and then play those openings exclusively for the next month. In a month from now, look me up and tell me your rating.
You'll learn more than the 2 openings. You'll understand how to develop your pieces and why you're doing it in that way. You'll keep your position tight and not leave pieces hanging. More than that, you'll learn how to create a plan for the middle game.
As above, tactics and end games will improve your chess.
Run the computer analysis after every game and think deeply about every mistake you made. It won't take long and you'll have those openings mastered, I assure you that if you don't make a mistake in the first 10 moves of the game, and you have a plan, you'll move up quickly from your current rating.
Boris Spassky once said that he wished he could forget everything he knew about chess, and start over.
"... for those that want to be as good as they can be, they'll have to work hard.
Play opponents who are better than you … . Learn basic endgames. Create a simple opening repertoire (understanding the moves are far more important than memorizing them). Study tactics. And pick up tons of patterns. That’s the drumbeat of success. ..." - IM Jeremy Silman (December 27, 2018)
https://www.chess.com/article/view/little-things-that-help-your-game
https://www.chess.com/article/view/how-to-start-out-in-chess
https://www.chess.com/news/view/a-new-years-resolution-improve-your-chess-with-new-lessons
"... In order to maximize the benefits of [theory and practice], these two should be approached in a balanced manner. ... Play as many slow games (60 5 or preferably slower) as possible, ... The other side of improvement is theory. ... This can be reading books, taking lessons, watching videos, doing problems on software, etc. ..." - NM Dan Heisman (2002)
https://web.archive.org/web/20140627084053/http://www.chesscafe.com/text/heisman19.pdf
"... If it’s instruction, you look for an author that addresses players at your level (buying something that’s too advanced won’t help you at all). This means that a classic book that is revered by many people might not be useful for you. ..." - IM Jeremy Silman (2015)
https://www.chess.com/article/view/the-best-chess-books-ever
Here are some reading possibilities that I often mention:
Simple Attacking Plans by Fred Wilson (2012)
https://web.archive.org/web/20140708090402/http://www.chesscafe.com/text/review874.pdf
http://dev.jeremysilman.com/shop/pc/Simple-Attacking-Plans-77p3731.htm
Logical Chess: Move by Move by Irving Chernev (1957)
https://web.archive.org/web/20140708104437/http://www.chesscafe.com/text/logichess.pdf
The Most Instructive Games of Chess Ever Played by Irving Chernev (1965)
https://chessbookreviews.wordpress.com/tag/most-instructive-games-of-chess-ever-played/
Winning Chess by Irving Chernev and Fred Reinfeld (1948)
https://web.archive.org/web/20140708093415/http://www.chesscafe.com/text/review919.pdf
Back to Basics: Tactics by Dan Heisman (2007)
https://web.archive.org/web/20140708233537/http://www.chesscafe.com/text/review585.pdf
https://www.chess.com/article/view/book-review-back-to-basics-tactics
https://static1.squarespace.com/static/5856bd64ff7c50433c3803db/t/5895fc0ca5790af7895297e4/1486224396755/btbtactics2excerpt.pdf
Discovering Chess Openings by GM John Emms (2006)
https://web.archive.org/web/20140627114655/http://www.chesscafe.com/text/hansen91.pdf
Openings for Amateurs by Pete Tamburro (2014)
http://kenilworthian.blogspot.com/2014/05/review-of-pete-tamburros-openings-for.html
https://chessbookreviews.wordpress.com/tag/openings-for-amateurs/
https://www.mongoosepress.com/catalog/excerpts/openings_amateurs.pdf
Chess Endgames for Kids by Karsten Müller (2015)
https://chessbookreviews.wordpress.com/tag/chess-endgames-for-kids/
http://www.gambitbooks.com/pdfs/Chess_Endgames_for_Kids.pdf
A Guide to Chess Improvement by Dan Heisman (2010)
https://web.archive.org/web/20140708105628/http://www.chesscafe.com/text/review781.pdf
Studying Chess Made Easy by Andrew Soltis (2009)
https://web.archive.org/web/20140708090448/http://www.chesscafe.com/text/review750.pdf
Seirawan stuff:
http://seagaard.dk/review/eng/bo_beginner/ev_winning_chess.asp?KATID=BO&ID=BO-Beginner
http://www.nystar.com/tamarkin/review1.htm
https://web.archive.org/web/20140627132508/http://www.chesscafe.com/text/hansen173.pdf
https://www.chess.com/article/view/book-review-winning-chess-endings
https://web.archive.org/web/20140708092617/http://www.chesscafe.com/text/review560.pdf
Deranged! Thanks for the input and checking out my game. That game was going well then I looked at his rating (I purposely don't look at my opponents rating on focus mode) and started to play differently. Choked basically. Just for fun I'll mention that I beat him in our rematch!
If you'd like a great opening for white, have a look at the London, it's not played very much and will catch a lot of players off guard. Lots of good videos on it too. You'll have fun playing it. Watch the GingerGM's videos on it but don't always play it quite as aggressively as sacking pieces can backfire - try playing it in different ways and see what you prefer.