lol good luck riot with its MMR system tries to keep you at a 50% win rate
its kinda how you climb... your mmr and rank goes up as long as you win over 50% and the longer you do this they adjust the mmr to make it harder and harder to maintain a 50%+ win rate and when you get to the point where you "plateau " and win rate starts to even out at 50% and you dont go up any more they determine that is the skill level you are suppose to be at
Pick a champ that can carry and only play it. Make sure it's frustrating to play against.
Kinda hard to say anything with simple stats.
If you want good help, post a gameplay of one where you lost, and thought that something you did impacted the game so that you got the loss
You could cs better.