Melissa, you can not help but smile and be happy at the most magical place on earth!
Obviously this is not the trip where you stay in the parks until midnight and attempt to ride as many attractions as possible. This visit move at a slow pace and enjoy the time with your toddler before the baby arrives. Reach the parks at opening and enjoy a full morning before your energy fades and take a break after lunch when the crowds and temperatures are at their highest. Spend lazy afternoons floating in the pool and napping in your dark, air conditioned resort room.
While in the parks, seek out longer lasting attractions such as "it's a small world" and the Walt Disney's Carousel of Progress that allow you to be off your feet for a few minutes. Sometimes Cast Members at the Tomorrowland Transit Authority PeopleMover will allow you to stay in your seat for a second go around for times you are feeling too exhausted to walk.
Consider booking an event such as the
Pirates and Pals Fireworks Voyage that has high entertainment impact and food but involves almost no walking. This special event has a pirate meet and greet, delicious desserts, and a relaxing cruise across the Seven Seas Lagoon to a spectacular viewing spot for the Magic Kingdom fireworks.
Remember to take numerous, frequent breaks to eat Mickey ice cream!
If you have additional questions please contact me. I've made multiple trips to Walt Disney World with infants, toddlers, and babies in utero and would love to help.