I have been on generic for Ortho Lo (tri sprintec) for months. I have a 28 day cycle always on time a day or two into placebo week however i dont take the placebo pills. Periods usually last between 5-7 days. This cycle day 3 of my period was light flow and I had unprotected sex. Within several hours bleeding stopped completely. I am not due for a refill of BC for another week. Could I be pregnant?