What should i do with a irutating classmate?

a girl at my school always spreads rumors about me and says i stuff my bra and i dont even wear a stinking bra because i havent started the growing stage yet so she also calls me and my friends bitches and other things then she says she didnt do anything there is only 3 days of school left and she punched me on friday what should i do she wont get iss or oss because the principal will say you should have spoken up befire but she pays people to say she didnt do anything so she always gets away with everything