Hey man I would first try and take a step back and make sure your having fun. No point in playing if you get upset every game. Its cool that you want to improve and it sounds like you have been trying to. Learning this game definitely takes time so I would not be too hard on yourself. Even after only two years your ranked right in the middle around the 50% mark, which is not bad at all. There so many champions, items, and other things to learn so it does take time. It sounds like right now you are still testing your limits as far as champions and damage while other players around you are more aware of their limits. This does take time to learn.
You say you feeding a lot and get flamed. When you are laning verse someone who gets ahead of you in levels or kills how you playing that match up? A lot of players try to keep fighting a lane opponent who is ahead and it turns into them feeding and putting the other player more ahead. It takes time but learning to play from behind is important. It comes down to trying to safely cs and farm up and waiting for assistance and to make plays later in the game.
Getting used to looking more at the mini map is huge so keep trying to get better at it. Most of us are not pros at it, but I can definitely say map awareness is huge.
You don't have to improve at everything at once. Sometimes you look at pros and they give lots of tips and some of those tips are important but only at a high elo level. Just focus on some basic things and work your way up. That's what I have focused on and once I get better at some things and get more comfortable then I start focusing on other aspects of my game.
