when is enough...enough

my grandpa brought me 16 dollars to pay for index cards, and bus fair. when I went to my moms job she waited until we left to say that I hurt her feeling because I didnt ask her if she needed anything, but I needed those items for school. Then she went on and on about it, and it was so annoying. I try so hard to the best daughter that I can be...I'm in a early college, Itryed to look for a job, I dont back talk, I dont do drugs, I dont have sex, and I just got the merit roll. Who would possible fing fault in all that? My mom can. I can totally understand why she's upset I mean she basically a single parent with two kids, but she always takes it out on me, then she starts crying.