Hi, I am 20 weeks pregnant currently. I had unprotected sex with someone other than my husband (we were separated at the time) on 2/15/10. I had a light period that was later than normal on 2/25/10, then another period 3/25/10. My husband and I got back together and had sex on 4/4/10 & 4/8/10, he "pulled out" both times, so I was shocked when I found out I was pregnant in early may. The dr. did an ultrasound on 5/13/10, says I was 6weeks 4days pregnant, due date 1/3/11. He said I conceived about 4-5 weeks prior which would put me at early April. Ultrasound 5/27 says 8weeks 4 days. I had another u/s at 17 weeks and it was a few days ahead, due date 12/30/10. Is it possible i could have conceived back in February and the ultrasounds are 6-7weeks off? Or can I be absolutely certain my husband is the father? I just want to be certain, I am so stressed about this, even though my doctor says I conceived in early April! Thanks ladies!