If your cycles are irregular, especially if they are "SO irregular," the period given on a conception calculator (which is imputed from the size of the embryo) will not necessarily match when your period was. So what. The ultrasound sees the actual embryo. It measures the embryo. From those measurements, it says when conception probably was. From that implied conception day, it counts back two weeks, to get at an implied first day of your last period. But for a woman who ovulates (to take an extreme example --) five weeks after her last period, although the conception date will be accurate, the last period date will not be. So don't let that throw you off.
You had an ultrasound early enough for it to be quite accurate. It was nice of the ultrasonographer to say what she did, but it's really a waste of your time or hers or mine to speculate about what you would have been seeing if things were further along; we could speculate that if you had been 39 weeks, you would have seen a full-term baby -- what good would it do to have that conversation? I think you should believe what the professional ultrasonographer, who was there on the spot and doing her job, saw and told you. She is the one with the training and the experience, don't try to second-guess her on the Internet. (I've heard it said that when a doctor hears a patient say "I read on the Internet ..." he hears, "I read on the you- don't-know-what-the-****-you're-doing ...") Don't worry. You'll be able to confirm things again at your next ultrasound and your next.
Good luck!
Thank you SOOOOOO, SOOOOO much for responding to my situation. You've made me feel ALOT better about it. I just don't remember EVER having a period in November and I most DEFINITELY know I WAS NOT having my period the date according to the conception calendar says I should have. I only remember having one in October but thought it was around the 21st or 22nd of that month but the u/s tech said there was NO WAY I was correct on when my last period was otherwise I woulda been 10 weeks and 2 days(gestational age)and the baby wasn't measuring that far ahead. She said if I was right it would've had arms and legs sprouted at 10 weeks. Do you agree with that? Then I will let it rest and leave this post alone:)
Here is what the conception calculator says for a due date of August 8. Even if there are only three days between the men, it also has to be at your ovulation time for you to get pregnant, and it simply looks like the guy who was with you from November 8 on was the only possibility given your ultrasound measurements. Sperm doesn't live long enough in your system to last from the 5th of November to the 15th, or even the 14th or 13th (assuming the ultrasound was a day or two off, which is unlikely in this case because of how early it was.)
Probable date of ovulation: November 15, 2012
Possible dates of conception: November 11 to November 19, 2012
Due date: August 8, 2013 (40 weeks)
It's so close the time frame of sexual encounters with both men. My good friend and I slept together for te last time on Nov 5 & my hubby and I slept together from Nov 8 on. That's only 3 days in between men for the month of November.
The u/s technician dated my due date of August 8th 2013 when I went in for my appt on January 2.
8 week 0 days, on what date? In answer to your question, that should be at max only a day or two off or even spot-on, because it's so early. All the info you've given suggests it is your husband's baby.