My High Normal game MMRq

Hey everybody, I'm Deversal. I play a little bit of ranked here and there but mostly normals. (2000 normals played and about 100/150 ranked). I main (almost onetrick) Katarina and I'd like to think I'm decent at her. So decent that I've been getting queued with higher higher and higher elo. If I want to play with my own rank I'll have to play with my silver friends. OP.GG and also A few examples

Now with Katarina I manage to win this games due to a mechanical advantage but I can't play any other champs this way. I wanna try shit but I know that if I'm up against plats and diamonds I'm gonna get destroyed. Is there anything I can do about this?