I dont get it

A week ago, give or take, i was S2. Bow im silver 3 and im about to get demoted in about 3 games, assuming my losing streak keeps going. I don't get what im supposed to be doing. Last 6 games, i either went even or won lane. Of course, it doesn't always show in the match history since I get shit on by the rest of THEIR team that the rest of MY team fed. I know that there were parts that i coudl've played better, but i dont see what i can do better. One game its an olaf thats 4/0 by 7 minutes, next game its a 13/2 hecarim running right past my whole team to one shot me. ADC is my best role, but i don't see what i can to to win these games.

If that wasn't enough, riot decided to start fucking with me. My mmr is average and my winrate stays at around 53-55%, yet i lose 20 when i lose and gain 19 when i win. I read somewhere that if you win and lose equally you'll eventually climb.

So my question is: How do i win ranked games (specifically as ADC), and why are my LP gains so messed up?

~a salty silver Chalenjour