Which date do I go by?

The ultrasound is more accurate. You didn't fall pregnant on your LMP and they only use that as a estimated date until you get your scan. I'd go by the ultrasound date as that's the date they will also use.

You'll be due on the 2nd June then and will be induced on 12th June if needs be.

ETA - Ultrasounds are only off slightly if they are given after 14 weeks, babies grow at pretty much the same rate when between 7-14 weeks so that's why you get your first scan around this time.

You didn't fall pregnant on the first day of your last period otherwise you wouldn't have had that period as you don't get a period when you're pregnant.

They usually will always go off your LMP but they may go off how big/small your babies measuring. But only 5% of babies come on their due date. I know my babies are due 23rd april according to the LMP at the 6 week dating scan they said 24th april. But now they say 19th, 20th or 21st april. So really confusing but thats just because the babies are measuring bigger. They always ask for my LMP date though when they do the appointments. But either way my babies won't be coming on the 23rd April because they will be 40 weeks at that stage. They will be coming sooner they don't let you go over 38 weeks where i live with twins so il probably be due first week of april unless they decide to bring them sooner.

I just want to correct someones post from earlier, You can, and most women DO in fact get their period the first month of their pregnancy. By the time you miss your period you are already a month pregnant. (give or take).

Also if your confused then ask your doctor which date to use :)

They will probably go off your LMP. Ultrasounds are commonly off, around 9weeks an u/s is pretty accurate but after that it gets less accurate as you go. Up to 3weeks either way near the end. So they will probably go by the LMP.