Out of your top 10 most-played champions, your highest KDA is Kindred with 2.11. And that's your 10th most played champion in ranked, which means everything above that has an even lower KDA. That alone proves you aren't hard carrying games. And for the record, any champion you can truly carry a game on isn't noob. Actually carrying a game alone is difficult and takes skill.
As for your MMR, you've played over 1000 ranked games this season and have only won 521 of them. Your win rate is BARELY above 50%, which is why your MMR is so low.
Lastly, the amount of LP you earn per win is based on your MMR in comparison with the average MMR of your league/division. So because your MMR is lower than the league/division you are currently in, you are earning less LP on wins and probably losing more on losses until the game agrees that you have proved yourself a better player.