Have you ever thought about trying a different role? You know, back in the day when I was just stuck in silver all the time, I mained ADC. For a few seasons. I kept thinking top lane looked pretty easy. Champs looked easy, they were tankier so I would be less punished for mistakes, harder to gank, etc. So I made a smurf for top lane only. I got Gold in like 35 games. I just understood top lane and how to play most of the champs up there. I know you seem to like mid, but maybe trying to be a 1v5 Katarina mid-lane player just isn't for you. Or any of those Assassin-type midlaners.
Maybe you are better off JG, or Support, or Top.
See I know I would gain more elo if I just played top lane. http://na.op.gg/summoner/userName=treedayban Look at those season 4 top lane win-rates. Hell, look at current Sion. 100%. But, I dont care about gaining elo as much as I care about having fun. And I have fun teamfighting on ADCs. Hell, right now I'm having fun playing fill every game. Which means like 60% support, 30% jg, 10% everything else. So I just play what I want.
So, maybe do some self-evaluation on why being a mid-lane player, or even Kat player, is holding you back. You know why ADC holds me back? I suck at laning in a 2v2. I also, have little idea of what to do most of the game, outside of teamfighting. I can admit these things. I have little agency in a 2v2. I can never push any sort of advantage like I can in a solo lane, or even as support. I have more lane agency as a support. I have more map pressure and awareness in every other role than ADC. Sometimes I find myself just wandering around, getting cs, following teammates, hoping for the best. While I'm on support making plays, tping as a top laner, etc. I have impact I created. I can even see this in BETTER ADCs I face, who seem to get more work done when I don't.
BUT, I like playing ADC. I enjoy the mechanical aspect of it, so I continue to main it, despite me hurting myself LP-wise. I could just go play Sion top or whatnot and gain elo.