Why is my mmr so fucked?

I have definitly gone on wins streaks like 3-4 times having around 3-4 wins each time but yet I still get shit lp. It's kinda hard to do anything when I get 20+ lp los sbut only gain 13-16. And there are games that I have hard carried there is evne a 18/0 game where I less lp than going 6/3. It's so hard to climb when even if i win 2 games 1 game will take all my lp. What do you want me to do I go on winstreaks and that shit never changes.