Pregnant?

I have been experiencing several symptoms of pregnancy, nausea, dizziness, sore breasts, however I have had my period, and I've taken two pregnancy tests which have been negative. That being said, one would assume the answer is obvious, but my mom had her period for three months before the doctor confirmed her with me, and my husband's mom was pregnant with both boys and the tests read negative. Is it possible that I still could be and if so what should I do?