Late Pills and Antibiotics...Pregnant?

I have been on birth control for 2 years and occasionally take a pill late. Last month I took maybe 5 or so of them late, but always took them either later that night or the next day before my next pill. I was also on antibiotics for a sore throat. I went off the antibiotics on Jan 25th and was not due for my period until February 7th. I began bleeding on January 30th, light and brownish and it continued until when my period was supposed to show, and became more "period like". I had unprotected sex on February 3rd and 4th, during the spotting/breakthrough bleeding time. I kno the breakthrough bleeding was because of my not taking pills on time everyday, but I'm worried I could be pregnant. Do you think I could get pregnant only a few days before I was due for my period during the breakthrough if the late pills and antibiotics had messed things up? I am not due for my next period until March 7th, so I have another week until I know if I'm late or not. Please help!