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