Hi Pamela!
You and your son will be able to ride most of the attractions, as most do not have any height restrictions/pregnancy restrictions. Here are a list of attractions that you would not be able to ride because of either a height restriction (and or pregnancy restriction):
Magic Kingdom:
Big Thunder Mountain Railroad
Splash Mountain
Space Mountain
Stitch's Great Escape (the harness might be uncomfortable for your baby belly)
Tomorrowland Indy Speedway (I would not ride pregnant because of the risk of being rear-ended)
Epcot:
Soarin' (has a height requirement, but is a very slow and gentle experience, I have personally done this one pregnant several times)
Mission: Space
Test Track
Disney's Hollywood Studios:
Tower of Terror
Rock 'n' Roller Coaster
Star Tours
Disney's Animal Kingdom:
Expedition Everest
Dinosaur
Primeval Whirl
Kali River Rapids
Kilimanjaro Safari (warns against pregnant guests riding, it's comparable to a very bumpy car ride)
Here's a
link to a page where you can sort attractions by your son's current height so you'll know what he'll be able to ride with you.
As always, all pregnancies are different, and make sure to consult with your doctor before your trip to address your specific questions or concerns. Keep in mind, I'm not a doctor, just a Mom.
Have a magical vacation!
Amanda