Hi There, I Have Been On Birth Control For About

Hi There, I have been on birth control for about 4-5 months now and never missed my placebo pill's. I had unprotected sex a day before ovulation then started getting a brown discharge / light bleeding on and off (only when wiping) a 9 days before my period is due. I skipped my placebo pills thinking that was just breakthrough bleeding because of my birth control pills but I am still bleeding on and off so now I am on day 11 of bleeding which isn't normal.
I usually have regular periods that last around 4 days. Could it be that I am pregnant?