Concpetion question.....PLEASE HELP

[Aliviacaleb2010]

I am pregnant with twins. I am confused about conception a bit. My LMP was 07/21/2010. It ended around 07/25/2010. I had unprotected sex with my husband the day it ended or the day after. He did ejaculate inside.  We split up in the beginning on August. I was with another partner late night on 08/04/2010. He pulled out. According to my LMP I am due on 04/27/2011. Google that and you get that I conceived between 07/28/2010 and 08/04/2010. I asked my nurse this question already and drew her out a time line and all. She looked up my first ultrasound I had on 09/28/2010. On that date it should one baby 9weeks and 3 days and the other 9 weeks and 6 days. She said according to that (with her pregnancy wheel) it would bring conception back to around 07/28/2010. Which would be my husband. I am just very confused and terrified and would love to know if my nurse was accurate. My husband and I are back together and would love to know that chances on who.....

[Clysta]

Even with irregular cycles, ultrasound and LMP both give a rough idea of when conception would have taken place. (especially ultrasound) Either way with both dates, DNA testing has to be done as the dates are far too close to even guess

[Aliviacaleb2010]

My periods have never been regular. Different people ovulate at different times. I could go months without a period and that was normal.....

[AnnieBrooke]

It seems, if your last period began on July 21, that the likeliest date for ovulation is about two weeks later, if your cycles are regular and of average length.  This would put conception closer to August 4, but do remember that sperm can live four or five days in your system after sex.  If you and your husband split in the beginning of August, you can't speculate on the difference between, say, August 1 and August 4.  The dates are so close that if your twins are fraternal, you could even have one baby from one father and one from the other.  You really are going to need to do two DNA tests (one for each baby) once the babies come.