I'm not trying to be mean, but at the MMR that is closest to your actual skill level, you should have about a 50/50 win/lose rate, as well as win/lose the same amount of LP per win/loss (give or take a few percent/LP, but on average).
This means that you are currently much higher than the system thinks you should be - you're being matched with players you should easily beat. The system is giving you very little LP on wins, and a very high loss on losses so as to get you to the correct MMR. Once you get there, you'll get back to 20-25 per win/loss.
Now, about trolls. Statistically speaking, you win more games because of trolls than you lose. This is because there are 4 opportunities for trolls on your team (not counting you), but 5 on the enemy team. Thus, you win about 10% more games than you lose because of trolls. Thus, while you are at a MMR matched to your skill level, trolls actually cause you to slowly gain LP.
Lastly, trolls are heavily punished - when confirmed trolling, the first offense is a 14 day ban. One game. 14 day ban. Second offense? Usually a permanent ban, sometimes a shorter manual ban (such as 2 weeks, one month, three months, etc).