Concerened. This is our rainbow baby all the blood work and test come back normal, but she is…

Concerened. This is our rainbow baby all the blood work and test come back normal, but she is growing at an alarmed rate. I'm 22 weeks exactly and she is already 2lbs I see the dr every two weeks and every four for ultra sounds. Today the dr said they may be moving up my due date on account of her size but will know after my next ultra sound. I guess I don't understand what that means cause I know exactly when I conceived and it impossible for it to be any other time.