Could I be pregnant?

I just need some peace of mind, haha.  My husband and I had unprotected sex on the 22nd of September.  My period was due yesterday, and I had cramps that constantly felt like it was coming.  I am still having cramps today though, and I still haven't gotten my period yet.  My breasts have been extreamly sore as well- they hurt more than they ever have in the past.  I have also been feeling slightly nauseous...but that could totally just be in my head. Is it possible that I could be pregnant, or am I just due to have a really bad period?