I am 20 years old. I have had irregular periods in the past, but this time it's been two months since my last period. My last period was October 14th, and I had intercourse on November 8th. Although alcohol was involved, we did use a condom. However, I have not had my period since then. When I was supposed to get my period in November I developed symptoms such as sore breasts, irritability, and some cramping, but my period never came. Now I have had those symptoms ever since. I took a pregnancy test December 13th (a little over a month after I had sex) and it came back negative. What could be going on with me?