Due date changes?

So, at my 20 week scan baby measured 1 week ahead. However, my OB says that 1 week isn't that much and they kept my due date at March 17th, instead of pushing back to March 11th. Now I'm somewhere between 32 and 33 weeks, measuring at 34 weeks in fundal height but still no change to my due date. Anyone ever experience this? Should I ask them to change it to March 11th? I dont think due date is exactly when baby comes but i dont want to have the baby say, February 20th and be told my baby is almost a month early when baby and I have been measuring ahead since week 20.