baby measuring behind

Hi ladies. When I went for my first OB appointment I was 8 weeks 3 days with a due date of 11/21, but baby was measuring at 7 weeks 5 days. They changed my due date to 11/25. When I went back 2 weeks after I was 10 weeks but baby was still measuring behind, 9 weeks 2 days. Changed my due date again 11/27. So this Tuesday coming up I go for all the blood work and NT ultrasound. The office is still going off my last cycle which will make me 12 weeks Tuesday but baby might be 11 weeks. I'm just so confused because idk if I am 10 weeks or 11 weeks right now lol. Have anyone else have this happen? Did baby eventually catch up?