Unprotected sex! Please help

Okay, so I had unprotected sex on the 10/9/15 and I'm 16 and I can't tell my parents and I'm not on the pill. How long should I wait to take a test? My period comes at the end of every month but I don't wanna wait that long to find out if I'm pregnant or not. Please give me your opinions on what I should do. Thank you!