MMR, questions/situation

Hello, I'm Ivam...I'm currently Gold V, my MMR is 1251 at the moment (Below the MMR required for my league).

I like playing with my Platinum friends because we get matched with other platinum players and makes it easier to win as nobody feeds and it's easier to 'come back', however...I've noticed that my MMR is still the same and doesn't increase...Despite not doing bad at all in games and sometimes even end up carrying Platinum players, also I've noticed that whenever I 'Solo Queue' I can NEVER win, it's almost impossible...Somehow other lanes go 0/14, people go afk, or they rage and quit. The point I'm making is, I find it almost impossible to win if I 'Solo Queue' as I often get paired with Silvers V (Which I'm guessing they have the same MMR as I do). Not being cocky but my play style is much better than most them as I've always been playing with Diamonds and Platinums since I pretty much joined league, my farm is 90% of the games better than everyone else's and I try my hardest but still my MMR is low and I can't win games 'Solo queue' If you guys could ADVICE ME on how to INCREASE my MMR, and maybe win more games, I would really appreciate it.

Thank you in advance, Ivam.