I'm sure your baby's fine and he won't be "huge". The difference between 31 weeks and 33 weeks is only 1lb.
Keep in mind, baby's gain just under half a pound a week in those final weeks, and even less in the 30-35 weeks. But, estimating half a pound a week, your baby only has 5 more pounds to gain between now and your due date, and it could easily be less. A 9lb baby is big, but not "huge", and lots of women safely deliver 10+ lb babies.