Could Lower Abdominal Cramps And Sore Breasts Be The Symptoms Of Pregnancy?

My last period was December 12. I was supposed to get my period again on January 2. On January 1, my husband and I had unprotected sex and I have yet to get my period. I keep getting cramps in my lower abdomen and lower back, my breasts are sore, and I feel bloated and gassy. I took a home pregnancy test yesterday morning and the result was negative, I took another one today and got the same result. I have had irregular periods in the past and just went off my birth control 3 months ago. Is it possible that I'm pregnant?