Could you help me. I had sex on June 1, 2014 with Guy 1. That was the only time. Then I had sex with Guy 2 June 10, 2014. I came on my period the very next day which was June 11, 2014. My Ultrasound says lmp June 6, 2014. On September 29, 2014 ultrasound put me at 16 weeks and 3 days. Who has more of a chance to be the father Guy 1 or Guy 2? I hope it's Guy 2 which is my boyfriend . We were going through a break up when it happened with Guy 1