My mother and I got into a very big argument over this.

In my school, seniors are the only ones not required to wear uniform. And so, the dinner being a semi-formal, students-only event I thought it perfectly fine to just buy a new dress...My mother on the other hand believes I am supposed to wear my SCHOOL UNIFORM. Nobody else is wearing theirs!
I don't know where she got this idea, and it's not like I even have a uniform - I gave it to my sister.

What am I supposed to wear now? I can't convince her not hire a uniform, and there is no way I'm wearing my dress from my school ball but no other dress I have meets the dress code requirements. Either way I feel I'm just going to be humiliated at the end of it all.

Is it better to go in uniform? Or should I use the money to buy a dress? I'd borrow one except no-one I know is my size besides my sister.