Ultrasounds are most accurate. Go by that.
Go off the ultrasound but if the due date changes by +,-7 days they usually don't change the date and go by the original because babies sometimes fluctuate in their growth but since yours is a pretty significant change, go off the ultrasound since they can actually measure the baby (: congrats and good luck!
Count back the weeks from your due date.
Well who knows cus my last period was feb 4 and my due date is November 11
Typically the ultrasounds are most accurate. I thought I was due 12/24/15 because of my LMP, but when I got an ultrasound we found out I'm due 01/09/16. I'm irregular and ovulated when I was supposed to start my period in April instead of two weeks prior. Could've been something off like that.
Yes i think it was based on the ultrasound
With my first I started my period the 25 of January and was due October 31st (leap year) but on a normal year it would've been Nov. 1st. Based on that, I would say that you would be due on the 7th, if you ovulated two weeks after the first day of your LMP. If you ovulated a week or so then perhaps it would be the 16th. Did she say why she thought it was the 16th, was it based on the ultrasound?