So I'm really confused about my due date. My sister and I did some calculations and I should be a lot further along then they say.

So they say I'm 28 weeks. But based off my last period, I should be 31weeks. How did they get that big of a difference?

I look a lot further along then 28 weeks too.

So my LMP was February 6th.

They said my due date is November 27th.

When I went for an ultrasound back at 20 weeks they said I was measuring 2 weeks ahead. So how did they get that due date when it doesn't even calculate right