How do I become a better player?

I have been playing for 2-3 years now, multiple games a day. 
It's in phases for me; Some weeks I am good and win most games, other times I lose pretty much every game. Currently I am in one of those lows again.
Just recently I broke through to 800 and was so happy about that achievement, and when I played other 800s I felt like "Why is it so easy now?". And it was. Almost every game I played that first week felt like "How are they making such obvious mistakes? It's a lot harder than 700s for some reason". Then I lost "it" and started losing myself. The worst part: The mistakes I make currently are also stupid blunders, and I could pull my hairs out. Yeah, yeah "play slower" but honestly? I think I am not practising well enough. Not sure how one is supposed to study chess. Like most of us I watch a lot of videos on chess tactics, sometimes I look at opening on chessreps and practice there, and I play puzzles. And yes, I play a huge volume of games.
But it#s not making a huge dent?
I thought that would gradually make me a better player, but I am a mere 800 elo player. Laugh at me all you want, but I genuinely just want to know what I can do. The current blunders, sure, they'll go away it's just a phase and I'll be able to concentrate again well enough. 
Just how exactly am I supposed to get a better player in general? Playing volumes is definitely not making me better.

Find a coach

It varies a ton from player to player because we all have different chess strengths and weaknesses. We can play one or two unrated rapid games if you like and I can offer some tailored advice

Sure, that would be nice. Send an invite, if you like. But beware, I am currently not feeling my best anyway and most mistakes that lead to a loss are obvious to me. Usually even the very second I moved.... I might blame it on that.
If you want, you can look at my recent games. I hit 800 around 19th november. Probably like 16th or so. That's when I played my best.

I tried that recently, didn't play a game for a week. Came back tilting still. This post is a mix between "I suck right now, I am tilting waahhhhh" and general advice, because I am not ALWAYS tilting yet despite playing since years, not making as much progress as I thought I would.

So I keep doing it. I keep playing, play blunders that I immediately regret and feel like I wouldn#t have played some time ago. But somehow I can't stop myself. Chess is not fun any moe and although talking and playing with Keiba was nice, I still ahve the same questions open on how to learn chess more effectively besides playing.

Look for checks and captures FOR YOUR OPPONENT. Once you will concentrate on it you will start to blunder much less. Once you will get to a state where you avoid most of blunders, you should start to study games of old masters to learn about middlegame plans. I started to play chess 37 years ago and most of the time we just replayed chess games from the books.

I forgot to say games with good annotations