When are your sonogram appointments?

Ercmp
I had a sonogram to get a growth scan/weight estimate at 30 weeks. The next one is scheduled for 38 weeks. Was just wondering if this is typical or if some people get more frequent sonograms towards the end? I have borderline gestational diabetes, so I am worried about the baby gaining too much weight or if anything should be monitored more closely? All of my on appointments seem to be soo quick, they ask if I have questions and seem to be in a rush to move on to the next patient. I am a nervous wreck and don't feel ready for this baby yet!