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 sagte she'd think about it , then the Weiter Tag she sagte "No, I don't' want to trade some thing that Du should be doing for some thing I don't want Du to be doing." I even looked up non-toxic, non-smelly nail polish! I need some Mehr REALLY GOOD reasons, please. Thank Du all in advance.