I made a huge mistake and had unprotected sex with a guy who means nothing and meant nothing on November 25th. Anytime before that i had unprotected sex with my boyfriend & in the begining of november. My last period date was around november 2 or 3. Lasted oct 29-either the 2nd or 3rd. It's December 10 and I have a positive pregnancy test but nothing is showing up on the ultra sounds so they think it's really early stage. Can anyone help me figure out who's it could be? Also I took plan B on November 26 a day after I had the one night stand. I'm so worried but I'm gonna get through this no matter who's it is.