I Am Taking Tri-Sprintec And At The Beginning Of This

I am taking Tri-Sprintec and at the beginning of this months pack I missed the first four pills, I didn't take any of the ones I missed and I've had unprotected sex. I was supposed to get my period today but it didn't show up and I always get it on the day I'm supposed to right away in the morning, but all day there has been no sign of a period.