I need help FAST!

Hi, I'm trying to convince my mom to let me buy nail polish again. She hates when I wear pants so I told her I would wear medium skirts for a whole year. She zei she'd think about it , then the volgende dag she zei "No, I don't' want to trade some thing that u should be doing for some thing I don't want u to be doing." I even looked up non-toxic, non-smelly nail polish! I need some meer REALLY GOOD reasons, please. Thank u all in advance.