I'm wondering if I should be concerned about pregnancy. I take Junel FE and usually have very regular 'periods' on the pill (28 day cycle). My last period ended May 17th and I had protected sex that day which seems an unlikely cause of pregnancy. I had a dental surgery June 5th and abandoned the pill pack then (mid month). I have been taking the antibiotic Amoxicillin post-surgery and am wondering if that could be the cause? Or perhaps it was stopping the pill pack?