How do I get help with my mom?

I am 15 years old and my mom doesn't like me. Right now she pawned every video game and DVD that i have and there about to get taken by the pawn shop. She doesn't care because shes never liked video games or DVDs, (shes a social person) and the thought of losing them doesn't even faze her. She takes advantage of me not being able to do anything by expecting me to clean everything. I have two siblings and they hardly have to do anything at all. My sister is 14 and all she can do is text, (which my mom has no problem with at all but if I play video games for half an hour she says that's all i think about) and my brother is insane, so he cant do anything. And to top that off shes always assuming that because im male i do all this stuff, like all i think about is sex and that im going to grow up and become a horrible person. None of that is true and it is pissing me off that she is being sexist. She wont even let me be on the computer for over 30 minutes because she always wants me to do stuff. Even more my sister has more privileges than me even though im well more behaved, like she can have all this food just for herself and text all day and not get in trouble but if i don't listen to my mom im all of a sudden grounded for a week. My mother wont even have a conversation with me at all and when i say something she just says, "Im done" and leaves the room and treats me like i have no feelings even though im very sensitive. She even goes as far as treating me like every thing i do is a disappointment I cant stand her anymore and i need some help with her. I don't want to talk to CPS because i don't want to be taken away. I just want her to actually listen to me and to stop treating me like dirt.