I'm 15 and my boyfriend is 18 and every time I see him we have sex. I saw him today and he came in me once, he said he's already came in me 5 times before and I haven't gotten pregnant yet. I'm not sure what to do but I'm scared because I don't want a baby right now. He said he would take of our child if I did get pregnant. But how long after having sex would i know if I'm pregnant?