I know they seem like they are never right when it comes to weight. When i had my first son they told me that because i was small and smoked at the beginning that i was lucky that he was gonna weigh 6 lbs. Well when he was born he was almost 9 lbs. I saw my regular ob and he told me to stick with the 5/21 date and thats what he is gonna go by to schedule my c section anyway.
I never had that problem, so no help with that, but I switched Drs. when I was 21 weeks, my due date was May 10th, then my new Dr. said a different date. Then he said we could stick with May 10th. But usually babies are measuring around 5 pounds on week 35, so maybe you aren't due til the 29th. But Drs. aren't always right when it comes to the weight. They told my sister my neice was measuring at 8 pounds on week 40 and when she was born she was 6 pounds. Then my other neice was 6 something when she was born and the Dr. said she was weighing around 7