Early pregnancy? Or just a pill mishap?

Soooo I have been on the pill for 4+ years and the other day I couldn't get my pill cause of the prescription being up and the pharmacy having to re-order it. Anyways, my fiancé and I have been sexually active for almost a year, we trust and rely on the pill, and don't use any other form of protection. We have never had a problem. Because of the pharmaceutical mishap, I was off my pill for almost 4 days, my period ending 4 days ago. We have had sex in this time frame, and he has finished inside me. My breasts feel tender and swollen and my uterus feels like it's vibrating or tingling, not painfully, it's actually added to my sex drive. I cannot stop craving my future hubby, the past few days, it's become crazy. Could this be an extremely early sign of pregnancy? Or are my hormones just out of whack because of the pill mishap? 
Update: I feel crampy and moody this morning, my uterus feels tender and sore. I felt nauseous earlier but I feel okay now. Any opinions?