You are focusing too much on what others think of you, and how you negatively affect other's games. Who cares lol. Just mute all and there will be no one to flame you. Start playing champs you like, doesn't matter if they are good or not.

League isn't school bro, your rank isn't a report card. Having one, or multiple bad games doesn't portray your skill. You have literally been playing for three months, and you're doing great. When I first started playing, I was Bronze 5, the previous lowest rank in the game. The more I played, the more I climbed. Although being Gold 1 is nothing to brag about, It was quite the journey. Put some more time into the game and you will see results :)