I always suggest people to be careful with their knowledge, you might know every single thing about the game, but your teammates won't, don't let this informational barrier lead you to have expectations that won't be met. Map awareness and realizing what your teammates are doing instead of assuming what they are doing is a pretty big thing.

Self improvement sometimes needs to occur during the game, and less on reflections. I played a game earlier, and I was extremely dissatisfied with my laning phase even though I was breaking even. I just kept trying that game and had really dominate team fights played pretty much as optimally as I could see available. We lost the game cause fiddle didnt ult in multiple fights, didnt secure baron twice, gnar went top to clear a wave without tp when our 5th dragon was coming up in 25 seconds. Was a bad loss, I was really upset.

But I'm going to keep playing, I didn't curse out Gnar or Fid, I didn't complain about Janna having shitty ward management. But it was just a plat 3 promo, I need to reach Diamond still, I want to aim for challenger or d1+ team. I'm nowhere near my goal at the moment, I can't care about this game but just see it as a game I can't misplay my laning phase that much.

Your goal needs to be re-reach gold 1. Your pretty far from that now so you have no reason to worry about a loss here and there. Then your goal for the season is start to climb through plat a bit, doesn't even have to be that far, just get somewhere, get high, fall low, rinse and repeat until your a stable skill level, even if it's not where you peaked.

If you never messed with customs, never used aram for practicing teamfights/skill shots with a serious mindset, willing to throw a game to try and expand your level of play/aggression. Those are some places to start. Some players just play and climb, some people just need to polish up on a few specific mechanics. My cs'ing at the moment is atrocious to the level I want it to be so I have been doing CS'ing drills even though I've been Diamond 3.

Maybe you just need to play to win, no worrying about teammates and stuff, just try to carry. Focus on killing and picks instead of objectives. You might end up losing these games but it could be a mechanic your just missing from your play that will help. I personally pretty much don't care what role I am, I will hard engage if my team wont. I've jumped in, got caught, and got out as ADC just to make stuff happen. Play making is sometimes that one thing that's preventing you from winning a game.