Oh my WORD.
The measurement that they do is CENTIMETERS.
This means you are 34 weeks, and your uterus measured LESS THAN one INCH bigger than "average" for 34 weeks.
This could be because of the position the baby was in, the amount of fluid in there, or just the way the doctor lay the tape across your belly. A different person might have measured you at 34 or 35... just based on their technique.
A two centimeter discrepancy between your belly and "textbook average" is NOT a big deal, not a legitimate reason to do an U/S, and NOT grounds for saying your baby is "big."
It sounds like this guy is fishing for a reason to induce/section you. Be VERY careful please! Ultrasound measurements can be off by TWO POUNDS +/-. It's not very accurate at guessing how big your baby will be, how much your pelvic ligaments will stretch, how well your baby's head will mold to slide through your pelvis... It's not like your pelvis is made of concrete, and your baby's head is a bowling ball! Your body was made for giving birth, and given HALF a chance to work as designed, it WILL work just fine.
Sorry the doctor is messing with your head.