had sex last friday and i was sopose to get period yesterday

Did you use a condom? Were you on the pill? Even if you did both of those things there is always a possibility you could be pregnant. Buy a preganancy test. Some of them will work this early, just check the box. Also, you can get the morning after pill the day after unpotected sex at the drug store if something like this happens again. Do not have unprotected sex! Preganacy is not the worst thing that can happen. Carry your own condoms and get comfortable telling guys that if they want to be with you they have to wear it. If you are not comfortable having that conversation, then you should not be having sex. Really not lecturing you (okay I am a little) but I just want you to be a safe sexual participant. It's supposed to be fun, not a cause for week later panic attacks. I should know, I was a fifteen year pregnant girl. Not fun. Be careful.