Missed day of birth control, unusual period, pregnant?

Patient: I am taking birth control and have been for a few years now, I am pretty good at taking it every day at the same time. This month I missed one day around day 8 of my cycle but caught back up the next day. My boyfriend and I have sex with a condom regularly; we had sex without a condom the first day of my sugar pills. My period is usually medium to heavy and this month it is pretty light and not enough to fill at tampon in 6 hours. The color was brown then went to a deep red and in now back to brown. The brown coloring is normal for me but my period is light enough to get me worried. Could I be pregnant? What is the possibility that I am?

Symptoms: Having normal Period symptoms such as light cramping (normal), and moodiness

Doctor: