Losing streak, how to raise my MMR?

I've been in a losing streaks for a few weeks. I'm playing duo on evening, and a few solo games during the day. Losing almost every time in both situations. Concretely, my question is: how to raise my MMR?

I asked Riot this question, their answer was: keep winning your games. Seriously? What do you think I'm trying to do? Dancing with blue golem as Popstar Ahri?

No need to tell me about farming, vision, map awareness, objectives instead of chasing kills, proper build, etc, I know all this. And I apply these methods ingame. So I don't know what the issue is. I'm not that future challenger player of course, but the level during my LoL games is so low and frustrating that I'm not having fun anymore, while I love the game itself. Most of time, I get matched with people of a clearly lower level than me: no flaming here, and I don't talk about divisions, I'm talking about their actions in game. (I'm really hoping you won't see me as a flamer here, that not intended)

Is their a secret tip that I don't know and would make me win my games? haha No seriously, am I missing something important? I reached Silver 1 before, lost promo to Gold. But since I went down to Silver 5 and I'm pretty stuck. I know I won't be matched with "better" players until my MMR is higher, but I can't figure out how to do so. Even when I lose, what I did during the game, doesn't it count to adjust the MMR?