Why do my parents hate me so much?

Alright i am 18 year old guy, my life was good and my parents are mad at me because of my grades i am trying my best but i am a slow learner, they understand that i am a slow learner but they get mad at me because of my grades i get like B's, C's and somtimes D' and E's i try my best at test but i seem to fail it i mean i do study yes but i have a disability of a learning comprehension but they dont take that too seriesly, since im currently unemployed at Aeropostale im having a hard time finding a job i live in Michigan, i havent payed my cell phone bill for 2 months and they took my service out, they took away my car and letting my younger sister being the main driver now i gotta ask her for a ride and yes i have my license and its embaressing, how can i get to track now? track season is comming up, im getting my homework down and everything, and i just dont like talking to them, when i talk to them each time they always complain about me and i get so mad i just wanna punch something, and they criticize my singing i mean i have been singing since i was a kid and took voice lessons for 4 years and i perform, people say im really good i dont even ask from them they just say that. Im proud that i got this far with my voice. other things are that i dont make that much friends as my sister, she says im weird im the one that that is more outgoing that her she is shy usually and she judges me alot. Im nice to other people i dont mean to use race but i am asian and i respect other races especially white people i get along with them alot. I am Fillippino, i dont know i just dont know what to do anymore i feel like my life is going down the drain. im not that smart, my goal is trying to get a 2.5 gpa for a dual enrollment cl next year and i hate to say this but im not graduating with my cl and my life is frustrating i just feel like i wish i was smarter and its hard to overcome my disability. im supposed to graduate this year in 2011 but i cant im graduating next year of 2012. I need your opinions i just cant think right now im just frustrated =(