Advice

I think I'm pregnant and I feel like if I told my boyfriend he'd be so pissed. We've been together for 3 years but he's always told me that he would leave if I get pregnant. Then I have my parents.. I'm 18 but I work and go to school for nursing full time. I feel like I'd probably have to move out. Oh and before anyone decides to judge.. I am on birth control but I was recently put on antibiotics, we always use a condom (except once) but he always pulls out. ????