What Causes Delayed Period While On Sprintec, Next Choice And Morning-after?

I am currently on sprintec birth control. I take my pills within a few hours everyday. On the day of the last active pill in my current pack I had unprotected sex. He pulled out before he came. About 30 hours later I took next choice morning after pill to be safe. It is now the third placebo pill in the pack and I still haven't had my period. Could I be pregnant?