Did I conceive/ovulate later than I thought?

[Lovingmylife2]

I know for a fact that my last period was Oct 17. Which would have put me ovulating on Oct 31.
I am currently pregnant and due Aug 3rd. Which coincides with a last period of Oct 28 and ovulation on Nov 11.
Going by the date of Oct 17,THAT I KNOW FOR SURE WAS MY LAST, I would be due July 24th.
I have had 3 ultrasounds so far. One being in December and I was 6w2d and that coincides with an August 3rd due date.
Then I had one in January that put me at 10w2d and that one also coincides with an Aug 3 due date.
And one in March that put me 4 days behind bumping the due date to Aug 7 (though the doctor didn't change it).
So, is it possible that I just ovulated late and got pregnant several days after I thought I did?

I had sex on Oct 30 and thought that that this would have been the date that lead to pregnancy. But, with the measurements, it looks as if sex during the Nov 6-12 window is what lead to this pregnancy.

I am just trying to pinpoint dates and I am very confused.

 

[melfy77]

Well sperm can live up to 5 days and implantation can take place up to 12 days (if I remember correctly) after fertilization. So that's 17 days, which is quite a lot and maybe you also ovulated later than usual. So nothing to worry about and congrats on your pregnancy

 

[tinymumma]

It's rare to have your Bub measuring exactly on time at each scan. If it varies by a week or more, then they will change your due date. Since it was only 4 days, I wouldn't worry xx At the end of the day Bub will come whenever they decide xx