How do I improve enough to stop getting frustrated?

So I am a bronze player, and have been for 3-4 years now. I am getting more and more frustrated with myself that I cannot get any better at the game. I have attempted to main carry roles, such as adc and mid lane, picked easy win champs like malph and annie and learned them to the T, and have even spammed the hell out of op champs, all to the same effect, getting to my silver promos and losing them over and over. I watch videos, study champs, practice cs, play 1v1 customs. I'm at a loss as to what else I need to do to improve enough to get out of bronze. If anyone in a higher elo can help me out and tell me what else I can do, it would be much appreciated!