Changing due date

Ok so this ultrasound based on my last menstrual period would have been at 9w5d. The baby was measuring 9 weeks. So I figured I was 9 weeks but I saw the OB yesterday and she said my due date in still June 11th?? So that makes me 10w5d today which would make this ultrasound right. Has this happend to anyone. I am diabetic and she told me if I don't have the baby by June 11th then we will schedule an induction! She said we don't want a 10lb baby lol!