Baby question?

My sister should be 28 centimeters right now around her belly but at her doctor appointment she was 34 cent. instead the doctor is going to give her an ultra sound later next week because the size difference but everything seems fine and that its not her gaining weight. I was wondering if maybe she is even further than they think she is and is due alot sooner than her 2 origanal due dates. Is it possible for her to be due alot sooner than what the doctors think or is maybe the baby just really big? she just had her sugar test today so she is prolly like 7 months pregnant? The other day my mom told her she looked like she dropped but I couldnt tell and her belly button has been popped out for a few weeks also, im not sure if that means she might be having this baby even sooner or not...

I would wait for the ultra sound and see what that shows. Could be twins maybe?

The ultrasound will be able to give her a better estimate of how far along she is. They will be able to take measurments of the baby and see how the baby is developing.

I thought twins when since the begining but now she is 7 months and they havent seen another baby so most likely its only one baby. the last ultra sound the baby was a couple onces bigger than what most babies are at his age. Since she has a ultra sound the 21st or 24th We will hopefully find out though.

She just found out she has gest. diabetes and her sugar was 198 when they gave her the test, and that the baby is in right position with the head first.