How can i ever get a relationship?

ok me and my mom have never had a mother daughter relationship . and she doesn't act like my mother. the only thing i can give her props on is feeding me. other than that its a whole different story. every since my baby bro was born (oct 2010) things has been different. like every time i ask a question she always answers in an attitude like i member one day i asked her how she doing and she said alright WHY? like why did yu have to raise your voice and then she gets mad when i TRY and tell her to calm down and then by that point she gets louder and louder. im 15 and i feel like i dint have a mother. my "mom" doesn't talk to me about anything . usually round this age moms would start talking to their daughter about yu know girl stuff but nope my "mom" doesn't do nothing all she worries about is the baby. and lately she has been ordering the baby sooooooooooooooooooooooooooooooooooooooo… much clothes offline but if i was to ask for a new church shirt its a problem either she say i ain't got no money (lieing) or she procrastinates. then when i try to make a joke just to start a convo with her she says dont play with me like wht type of mom dont have a playful side with her daughter like honestly i have a bag packed to run away cause sometimes i feel like a motherless child and i ant take it . im sick of dealing with her and her attitudes towards me but then she always want something from me. and the only time she "claim" me is when we qo out in public and sometimes when she tell people im her daughter, in my head i say "dont remind me" like thts how bad im hurtin." pls help me . any advice?