Wait until at least 14 days after you have sex and take a test. It is possible you are pregnant.
Do you want to be pregnant? If you aren't pregnant after testing in a few weeks, you should stop by a planned parenthood and get on birth control (or to your obgyn if you have one already). At planned parenthood, it is free and confidential if you don't want your parents to know. Also, for future reference, there is a pill called Plan B. You have to be 18 to get it at a pharmacy, but if you are under 18 you can get it at Planned Parenthood as well. If taken within 72 hours of having sex, it helps prevent pregnancy.
If you are pregnant, there are 3 options (abortion, adoption, and having the baby and raising it). However, I would not worry about any of that yet. Try not to be too anxious about it and worry too much, but take care of your body just in case until you are able to test and get results in two weeks. Good luck.