I had sex with a guy on July 16th the condom got stuck in me and didn't come out until hours later but I took a pregnancy test July 26 and got a negative and got my period July 27. I then had sex with my ex  the whole first month of August didn't get my period took a pregnancy test Sept 1st and it showed pregnant . I went to the doctors today and the ultrasound is measuring me 4 weeks ahead 27 weeks pregnant instead of 23 weeks pregnant which would make this the first guys baby instead of my ex's ! Please help me !!! Who do you guys think the father would be ????