Antibiotics and birth control!

I just started up the pill in early June and I got strep throat and needed to start antibiotics within a week of starting the pill and while I was on the antibiotics my boyfriend and I used other means of protection. I wasn't aware that you were suppose to wait 7 days after finishing the antibiotics to have "unprotected" sex(on birth control). So the day after I finished he came in me and it's been almost a month now. My last period was 2 days of spotting but I assumed it was just because it was my first month on the pill, until recently when I started looking it up. Just wondering if anyone else has been in this position and what the chances are that I could be pregnant.