I can't imagine how scared you must be. First things first, you need to find out if you are pregnant and the only way to do that is to test.
Second, I'm assuming you're scared because you know you're too young to raise a baby. Sex might feel good, but the fact that you can't even drive yourself to buy a pregnancy test - please, please, please hold off.
If you can't get the test yourself, you might have to 'fess up to your mom. (And if the thought of that scares you, use that as a deterant to getting yourself in this situation again).
Rae (27), DH (26), Lucas (6/3/12), #2 due in December