Im 28 weeks pregnant and have very irregular periods. One month ill have it and the next two months i wont. So on. Very irregular. I took a test and was positive so i had an ultrasound done on May 12 & they told me I was 5 weeks and 1 day. never told me a due date since it was just a Planned Parenthood U/S. So I had an appt with my OB on June 10 & he told me I was 9 weeks and 3 days, ever since then my due date has been January 10. Never has changed. My boyfriend and I ALWAYS have sex unprotected and he always cums inside me. We have sex every 2-3 days and I know sperm last inside 3-5 days so im guessing its constantly inside me. Well one day, i did something I regret and cheated on April 20, i used a condom and he didnt cum because I kept freaking out. Although, precum was present inside the condom. Hes also 16 years older than me (39years old) drinks and smokes regularly which may effect. Ob said i conceived on April 17. But everywhere online says April 19. Can anyone help to let me know if theres ANY way I can have gotten pregnant April 20? Im pretty sure its my boyfriends but still get stressed out every day of this pregnancy that out of all days we have unprotected sex, i get pregnant the same week as the one night stand. Its killing me slowly. The guilt is tearing me down.