I'm 16, had sex 4 months ago, and afraid im pregnant. help?

Question: This is important, of course. Have you had menstrual periods since? Is there enlargement? You can get a preg test kit at a pharmacy, but if you have had menses, then you are not pregnant.

Big question?: Have you had a period since you've had sex? If you have, then you can't be pregnant. If you have any doubt, go to the drug store and get a test. They are pretty cheap and very accurate. And if this is going to be a recurring event (sex, I mean) get yourself on reliable birth control, then you won't have to be so stressed.