Should I update my weeks?

So from the start, we were never exactly sure on the conception date but at my first appt I was estimated at 8 weeks. Next scan at my anatomy scan the doc said I looked as if I was measuring at least a week ahead. And got another scan at 30 weeks, who said I was measuring about 2 weeks ahead. They guessed babies weight to be 4.8 pounds. So after another test for gd, which I passed, the doctor said if I make it to term he'll be a very big baby. She was talking about the possibility of c-section and whatnot.

Anyway, think it would be a good idea to move up my apps to like a week ahead? Did anyone else experience or do this?

Thanks ladies!