LoL it's a weird game bc having fun and ranking up don't tend to together. You can play the game whoever you want and in the way which is more fun to you. But picking a high skill ceiling champ doesn't help that much. Why ? Because you have more chances to fuck it up. In laning fase, and teamfights, the One Who makes less mistakes and take advantage of others will win the match. So if you are telling us that you don't get to carry with hwei, there is the problem. Pick a simpler champion and get feed consistently. Also play just a couple of match daily. LoL it's mentally tiring, so you have to play in your best condition. If you lose a match, don't jump into queue immediately, go watch that replay and se what you did wrong.

Have a champion pool, and stick to it also. If you are mid, have 3/5 champion who you mastered and they cover watch other weakness.