Could I be pregnant?

I went to my gynocologist 2 weeks ago because I suspected that I was pregnant. The cyst that froms each month in case the woman gets pregnant had burst (normal) on my right side but remained on my left ovary. My husband and I had had unprotected sex about 1 week prior to that apponintment, so about 3 weeks ago. Because of that last incident, my gynocologist said it was possible that I could still get pregnant from that last time, but that it was too early to tell by ultrasound. My period came last Friday and lasted for two days with average flow. Since, I have had light discharge, for about 7 days. Today, l have had cramping and am horribly nauseous, even after taking a nausea pill prescribed by my gynocologist. Is it possible that I am pregnant, or was my period enough to ensure that I am not?