What if it happens in school?

Hi, im 13 going on 14 and seem to be having symptoms that im starting my period. my sister started at 13. im really worried that it may happen in school as we only have a week and a half left and i have experienced white discharge every day for a couple of months. when i look between my labia there is a lot of discharge and yes i do wash. what if i get it in school , today i had a pain so bad i lurched over my desk, help?