I'm 21 and have been taking the same birth control regularly for the past 4 years or so. I recently had to start a 4 week cycle of antibiotics (both amoxicillin and metronidazole) to fight an intestinal infection. So far I have finished 3 weeks of the antibiotics and have only one more to go. I have heard that antibiotics can cancel birthcontrol, so we have been using alternate forms of contraception since I started the antibiotics to be extra safe. However, I accidentally missed the first 3 pills of my pill pack due to a combination of me not realizing I was on my last pack and not having any refills left before I went on a trip. I got my pill pack as soon as I returned and have been taking them again regularly. Unfortunately my boyfriend and I had sex ONCE without any kind of backup contraception since missing those first 3 pills of my pack (not to mention the fact that I'm on those antibiotics) and now I am starting to freak out. I know there is always the possibility of birth control failing, especially if you miss multiple pills or are taking antibiotics, but I guess I am wondering how freaked out I really need to be. What are the chances that we got pregnant since I missed several pills and am also on a strong antibiotic regimen? Any thoughts or help would be greatly appreciated