I feel you. I've been hanging around between silver 2 and silver 4 at the moment. I go on win streaks, but then get pushed back down.
I'm typically (and have more than once in the past) got up as high as gold 1, but can't beat that promo series to plat yet. Games have been difficult for me lately too.
I like to play mages mid and I play for macro as well. I'm a team player in general (I want to help my team when I'm in a game, and I don't need to be the solo carry, which is why I also like tanks in the JG).
Right now it's tough. They have put so much orientation on team play that it's not enough to do well and help your team carry, you also have to stop your team from doing too many dumb things. Trying to keep your team on key with a bunch of solo que strangers when one person can easily throw the game is not fun. Damage is so high it's really easy to get 2 shot yourself as a squishy mage (even with defensive items) or have allies who are constantly getting caught. It's not possible to solo carry in the current meta unless you are a crazy fed juggernaut or an assassin who is either unkillable or so mobile they can't deal with you.
Take for example Vel'koz. One of my favorites. I used to play him a lot, have had high WR on him for a few seasons now. I've tried playing him this season and he's just terrible. He dies really easy to all the high damage (literally have been 1 shot by a Kayn running through a wall with ghost blade and W in one game while I had a zhonya and 3 health items and insta died anyways) and there's so many anti magic shields now plus mobility that when someone gets near you guaranteed to die.
Another example is that there many champions who once an enemy ADC gets fed you are simply not ever going to be able to do anything to them ever. You picked a tank JG? They have a Xayah or Vayne with a support that can heal/shield/stun/peel? Unless your ADC is also fed that game is gone.
Eh sorry for ranting... it's just that I'm in the same boat. League hasn't been as fun for me for about 8 months now. I don't want to quit, but I'm not enjoying it as much.