Why is it impossible to raise my mmr back up to my current ello?

I am currently plat 4 but I am playing with an average of gold 3's which I don't understand. At one point I won 9 out of 11 games in one sitting and was still versing golds. I don't know what I am doing wrong but it is driving me insane that they put me against these people, that I consistently stomp, and get awful lp rewards. The formula should be simple, if you win games, your mmr should go up as such, instead it just stays the same with the way mmr is currently set up. http://na.op.gg/summoner/userName=Castle%20500