serious question, im loosing the desire to progress, how can i fix that ?

Hi, I have a problem, I feel like I'm training for nothing, because I have the feeling of "forgeting" all the training I did from one session to another as if I were starting from 0, as if I were starting again with a whole new sensitivity. With a high frequency of over/under shoot, which generates a lot of frustration, on all the aim trainer I have I must be at more than 100 hours, my aim at my top is really not bad but there is too big a difference between my level at the top and in general. In addition, in-game I noticed that my level changes a lot from one game to another, I explain: It's as if I suddenly forgot my crosshair placement, I forgot how to make micro corrections (from a point of view of knowledge of my aim) etc. The problem is that it makes me lose the desire to play and even the desire to progress, which is quite frustrating. Would you have any advice to give me, to the point I am open to all ideas.