Sick of SBMM

Some of you will say that it doesn't exist, but I'm TIRED of starting to play, that I'm good at a few games, and that the next day or after a while, I only play in games in which the rival team massacres us and beats us by beating. I don't know if it's matched by win or kill ratio, but it's very tiring. Yesterday I had some good games and I killed a lot, because today I get involved and in the 3 that I have played, all games in which they beat us and nothing can be done. I've been like this for months and it's already tiring