I constantly feel depressed

Find your niche as a role/champion, and whenever you make a mistake think of what you did wrong and work on it. The game is very unbalanced like more than usual at the moment too so its not completely anyone's fault.

First, I wouldn't get too upset about it. It's just a game. When this happens, ask yourself, "How much will this performance matter tomorrow? A week from now? A month from now? Do I even remember that time I fed mid a month ago?"

Now, as far as the game itself... I find rubberducking to myself works well. I verbally talk myself through everything I'm doing or plan to do and it helps me stay conscious of what I'm doing, what I'm missing, that sort of thing.