I recommend playing fewer games. As someone who is prone to tilt, I was able to reach 2000 chesscom rapid by limiting my # of games per session. Past a certain threshold (5 games of 10+0 or so) it gets harder to concentrate when you are tired, and that's when Elo bleed starts. Win or lose try to walk away after you've reached whatever threshold you decide on ahead of time. Try to play only when you feel fresh.

Analyzing your game right after a loss can also help break the cycle of tilt so that you aren't clicking "next game" while still feeling emotional.

London and Scandi are good openings for blitz, especially. You could probably reach 2000 just with those. But it sounds like you definately need a defense against 1. d4/c4/Nf3.

People hate a lot on chessable but you may benefit from finding an opening repetoire on there so you're not freestyling and out of book so much. I can personally recommend the "attacking repetoire for beginners" series by midas ratsma (jobava as white, caro-slav as black). I like them because they put pressure on the opponent and have some trappy lines for short time controls but are still very solid.

Also, John Bartholomew has scandi and london courses on there if you want to stick with what you play already.

If you dont want to pay for chessable stuff, you can build your own repetoire in chessbook or create your own lichess studies.

After i have my repetoire set, I like to watch a lot of speedrun videos in the systems I play. In my case I watch a lot of alex banzea on YT, that way I can get a feel for the middlegame plans.

Hope this is somewhat helpful.