You very well might know many of the basics like opening principles (if you don't then here is something worth checking out: https://www.chess.com/blog/KeSetoKaiba/opening-principles-again ), but the main problem here is probably playing bullet chess. Longer time controls generally boosts your overall "chess ability" and understanding, so improving your rapid rating or longer time controls will likely improve your faster time controls a little naturally - this is not true the other way around; getting good at speed chess (like bullet or blitz) will probably not make you better at longer time controls.
I recommend playing chess games 10 minutes or longer on chess.com and maybe even 20 or 30 minute games if you can afford the time. Whatever time control you mostly play, you want plenty of "extra thinking time" so you aren't rushed and have time to consider new things. New things might be doing a quick blunder check or scan for hanging pieces, it might be seeing a good move but looking for a better one, or it might mean reassessing the position after some key moment of the game.
There are also some "tricks" to improve at speed chess, but they benefit the experienced chess player, so I'd come back to speed chess only after you've greatly improved with longer games.
Examples of some "tricks" so you have an idea what I'm talking about:
-Knowledge of basic "theoretical endgames" and checkmates. Not exactly a "trick" per se, but it is extremely useful to be able to convert a theoretical win while basically playing in autopilot quickly.
-Knowledge of opening theory because openings are not that important sub-2000 rating (well to a degree anyhow), but knowing opening moves by memory means you can quickly move with little thought for the first several moves and this saves time on your clock. If you have some opening memorized 10 moves deep and it is played in the game, then that means that about 25% of the game (average chess game is 40 moves long) you didn't even have to think much; you just moved off of memory! This is huge because that means you probably used way less time than your opponent "thinking it through" for the first time possibly.
-Tactical awareness: this is greatly connected to pattern recognition. The point is that better players (especially tactically alert ones) see things much quicker if they know more patterns and this can save time in speed chess.
*There are also "premoves" strategies and chess "systems" and other ways to save time to help the bullet player - however, the best way to improve in chess (speed chess or not) is to learn the game at a little longer time controls and then speed chess will come a lot more natural to you 
So I have done chess club when I was younger and all I remember was how to move pieces and how to play the game, the basics. Every time I play online I lose cause of time or checkmate. I need help with tips and tricks and help I guess. Sometimes I play on 1 minute and SOMEHOW I LOSE because I blew 20 seconds somehow??? Which never happened so I guess I played against a hacker idk. But I need help lol.