I need some help.

Hey, I play this game since mid of Season 5. I didn't have any idea how to play but i dont know why i loved the game. I made lvl 30 and placements got bronze 1 going 2 W / 8 L . I was rlly bad but nah you know beginners never start good. About 7 months i was stuck in bronze, and i even fall in bronze 5 . After 4 months i started watching pro's streams and i saw how many mistakes i make and i tried to fix them, with this i got silver 5 from bronze 5 in preseason. Made placements 8w / 2 l bronze 5 and i moved my account to EUW and played so many games and got silver 3 . After that i made a smurf on EUNE to play with some friends and got placed silver 2 with 7 w / 3 l. About 1 year i couldn't get gold 5, stuck at silver 1 then hard lose streak -> silver 4 then hard win streak -> silver 1 and again and again. I made a lot of accounts to play in higher elo's to learn the game better but same result . My problem is that i play 6-12 hours everyday and I improve very very very slow . Never got higher than silver 1, i played with and vs golds plats diamonds and i know how it is but i rlly cant get higher division .

And on this account in placements were only weird games where enemy team had 30 kills in min 15 and my teammates going yolo tryhard flash tower BOOM " An Ally Has Been Slain " later "An enemy is legendary". I really can't carry if my teammates are going tryhard.Pretty much every game was : Or my teammates feeds , or enemy teammates feeds. A game was like 4/11 - 3/12 - 5/15 and something like this...

How should I improve faster and better ? :D