Why do i feel like this?

My mom and i are never in a good state in our relationship. She takes advantage of me for getting her things and cleaning the entire house while all she does is sit on facebook. I have a younger brother who is allowed to do anything and everything he wants. I dont understand why she picks on me. I do everything she asks and more and when i say one little thing wrong she goes into a playing the victim rant. how can i try and improve my relationship with my mom?