Asking again since I had no response!

Natasha • 21, A happy wife, and a proud mommy to Josiah! Life is sweet, and I always try to stay positive! 🌞
I'm 28 weeks and went to the doctor yesterday who said i'm measuring 31. He said if the baby grows more then we will do a ultrasound. Does this mean my due date can change again? Or is the baby just that big? This is my first baby so I really don't know much about this stuff...