I am floating between 800-900. How to increase my rating

Get a copy of “Masters of the Chessboard” by Richard Réti and study it thoroughly. Réti intended it to be a textbook and it is excellent.

up to 1200 you can grow doing nothing but solving puzzles

Don't worry too much, your goal should be to have fun with the game, and then, your rating will increase... or not, but if you have a good time, that's good enough.

I wrote a blog about things that I did to get from 800 rapid to still weak but better 1 500 rapid rating. I believe it can be helpful for new players and weaker intermediate players as well. Here goes:

https://www.chess.com/blog/nklristic/the-beginners-tale-first-steps-to-chess-improvement

Your rating is higher than mine but after looking at a couple of your games I see the same kind of blunders that are in my level.  nklristic's blog above has great advice and John Bartholomew's youtube videos's really are gold, and he makes a good point that blunders are the bane of the growing player and until you can stop blundering, it's hard to advance.

I've gone from 10 min to 15 and 20 min games so I have more time to scan the board after every move, and I have to tell myself to do that rather than move quickly because the response is "obvious".  Tactics are critical and I try to spend 30 - 60 minutes a day on chess.com puzzles.  I also try and develop my pieces to the center and only use one opening, e4 e5 on white.

I think if you play a lot of 10-mins games the grasp of chess will become much better

10 minute games are probably too short for a beginner who wishes to optimally progress. They are not as bad as 3|2 blitz games, but you don't get to think about the position as a beginner in 10 minutes.

1. Play 15:10 time controls or longer

2. Practice Tactics

3. Don't blunder

4. No bullet or blitz

5. Don't go for cheese, develop pieces and castle.

6. Git gud

number six hurts my soul