How big is big?!

So at my growth scan today my baby is measuring 2 weeks ahead of schedule. I'm 29 weeks and he's measuring 31! Putting him in the 94th percentile. His estimated weight is 3lbs 7oz! Is this big for 29 weeks?! Am I gonna have a 10 pounder?! My first one was born 2 weeks early and only weighed 5lbs 13oz. My ob/gyn told me that day that i probably can't have a baby bigger than 7lbs cause my birth canal is small and I'm a small person. I'm happy he's growing and getting big! But I'm scared lol!