3rd trimester sono scare

During my 35 weeks sono they did measurements and told me my baby was 7 lbs 6 oz already, also saying his abdomen is measuring larger than the head. My doctor started to almost push the idea of a c-section on me. (I am not against if medically needed of course) I have already had one successful vaginal birth and would like a shot at having another with this one. He just scared me with the options, saying the baby could get stuck since the abdomen was measuring larger than the head. How accurate are those scans and should I be worried? I am going to see a MFM doctor at 37 weeks to try and confirm the babies size.

I am also having period like cramping in the front and in my back that is coming and going like contractions just not super consistent yet and increased back aches. The doctor said that the baby can come on his own with it he next two weeks and that would be fine. I never worried about this with my first because I didn’t have a 35 week sono, I thought he was going to be huge, he was only 7 lbs 14oz.

Help ease my mind with any helpful info you have please!!! :(