Pregnant?!?!

So I just got on Birth Control about a month ago and it's my first time taking it and I'm almost on the last pill. My boyfriend and I are sexually active. We started having unprotected sex on the 2nd week of the pill and we have been having unprotected sex since then. I woke up this morning with my period which is on time and it was very light and now that it is night time it's barely even there.