You should have talked with your mother about this issue and learned that you can get some real bad diseases and also HIV from unprotected sex. Did the boy not respect you?? Was this your first time?
Please see your doctor as soon as possible.
You are old enough to have understood what you were doing, if not, then please learn more by checking the links below..
If you miss your period next time, then sorry but you will become a mother, and I don't really think that you seem responsible enough to be a mother yet. You must talk to your parents about this, or the school conselor!
http://www.ovulation-calendar.com/
http://www.plexxa.com/s/fertility_calendar These are calendars to let you know if you are firtile even when having a period
Check out the following site, it will help you through this a little more to reassure if you are.
http://www.babyfit.com **This one is free to join and has it's own forum. Also covers other questions you might have, diet, exercise, medication and clinical procedures. etc.
From now on, please make the boys respect you enough to use protection, if not tell them NO.
I am not judging you, just wish you got more educated before you experimented, that's all. I wish also that you are safe this time, and that you will watch out better in the future. Good Luck. Please keep us posted..