I followed advice and got better but I am now stuck.

After having a disgraceful season start to Iron 3, I asked for advice on a previous post on this sub. The advice was just too stop switching champs and to play 1 - 3 champs. I climbed insanely hard with this advice and got to Gold 4 in a very short amount of time with an insane WR, KDA, etc. However now that I have gotten to Gold 4 the games have gotten tougher, and in alot of games in teamfights now I struggle to stay alive because it feels like everyone on the enemy is just running for me. I try and take first pick and blind jinx every game, but it feels like I incentivize the enemy to pick multiple divers/assassins just to shut me down. I feel like I have hit a wall and I feel lost again on how to get better.I realize that the champs I play is likely not the issue however it feels like I have just hit a wall when it comes to jinx in these games. How do I improve: hitux#6546 - Summoner Stats - League of Legends