What is wrong with me?

Study chess books is very good teacher. And Study taktice puzzles.

Study taktics.

My rating went up when I did two things, played slower and did tactics puzzles. I stopped playing blitz and played only 15 10 standard. It gave me more time to think. Gave me a chance to see more tactics and mates. Playing slower will improve your blitz, but only playing blitz will make your chess worse. 

Tournament players spend several hours playing one game! That gives them the time to do many things, develop middle game plans, calculate deep on critical positions, calculate even deeper during the endgame phase, where one slip can cost you the game. 

After all that thinking spent per game, they develop skills that transfer to faster time controls. 

I was a band teacher. I had my students practice scales very slowly, so that they didn't practice mistakes, didn't develop poor technique. Same with chess, play slower, work really hard on removing one move blunders first. Be as precise as possible on calculating captures. Over time, all of these things will become faster, and you will then play blitz with much greater accuracy. Just like my students playing scales at fast tempos, they had to start slow and build up their speed. 

https://www.chess.com/article/view/study-plan-directory
"... 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
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

I was pleased that anyone got the reference.

Play longer games. Obviously.

Might be an allergy. d4 makes the board look rectangular to me.

"Put it back dammit - psychic beam"

Indeed. Your main problem is that you correlate your wins & losses as part of your play. It's only cool if you just simply enjoy playing, it's another thing if it starts to wear on your mind (thinking of only your overall record). True, wins & losses reflect most of one's skill, experience, mindset (in real-time) but get over that and I promise your play will get better. (ps extra studying time would help too) best wishes

I'm back in the 12's for a couple weeks. Still up and down as expected, but generally winning games I should win. Most importantly I'm seeing the board better. On occasion I'll hang a piece, protect pawn structure instead of my king, or miss tactics until after I move, but it's getting rarer and usually I can say that was dumb before my opponent moves.

Thanks all for your advice. 

Besides studying, playing longer games and doing tactics, in blitz you can also try to flag your opponent. In games without increment moving fast is more important than doing the best move. 

It sounds like you're going through a tough time in your chess games. It's normal to have ups and downs in your chess journey, and it sounds like you're in a down phase right now.

Checking in to see if in 2023 you're doing better!