help
I am in the same situation so I can't tell you what to do, but I'd be more than willing to work up together!
First of all, you have only played 10 rapid games with gaps of days/months in between games. That's not enough games to see any skill improvements. You also need to play every day. You can't not play for days or weeks at a time and expect to improve.
Let's examine some of your games:
This entire game you played in 30 seconds when you had 10 minutes on your clock. Chess is about thinking and you missed out on many opportunities because you didn't spend time to think before making a move. To improve, you need to make sure that every time before moving you look for checks, captures, and attacks. You did a good job in the opening developing a couple of your minor pieces. But you weren't looking at the squares they attack and didn't ask yourself what your opponent was trying to do; what their plans were.
3)If you are serious about improving, do not play blitz and bullet. There is a place for those time controls once you have improved at chess and certain moves and positions become instinctual, but you are not there yet. And in the mean time, you are learning bad habits.
At 300 rating, improvement usually does not come from learning more concepts, but from fixing a few repeating habits.
From what you are describing, the main issue is not opening or strategy, but consistency and attention during games.
If you play fewer games but review them properly, you will improve much faster than by simply playing more without reflection.
The key question is not “what should I learn”, but “what mistake do I keep repeating”.
If you want, I can help you identify those repeating patterns from a couple of your games and show you exactly what to focus on first.
Improving Your Chess - Resources for Beginners and Beyond.....
https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond
Over 5000 Award-winning Chess Tips - Dan Heisman...
https://www.chess.com/blog/danheisman/over-5000-award-winning-chess-tips
Dan Heisman's newest book "Maximize Your Chess Potential" presents a detailed discussion of 164 of his most important tips. The book is outstanding. (I own many of his books - all are excellent).