Hi, Rachel! It sounds like you guys could all benefit from a little dose of pixie dust! I hope the trip gives everyone a time to make happy memories!
Do you have a wheelchair? In the event that you don't, you can rent one at Walt Disney World. You will find everything you need to know about securing a wheelchair by clicking
Walt Disney World Wheelchair Rental Information.
When you arrive at the theme park, you'll want to pick up two things. A Guest Assistance Card is a huge help to people traveling in circumstances such as yours. The card will enable cast members at various attractions to help find the most comfortable accommodations for your family as you wait for shows to start or wait for your turn to ride something. This may mean providing you with an alternate line, an alternate waiting area, etc. They will do their best to make sure your wait is as comfortable as possible.
Also at Guest Relations, you'll find a booklet for guests with disabilities. It will go over things like which rides may need you to transfer from a wheelchair, it gives you companion restroom information, transportation accommodations, etc. The biggest piece of information you'll probably need is how the attractions work with regard to getting on and off in a way that will make it easier for your son.
Walt Disney World buses, boats, and monorails are all capable of accommodating wheelchairs, so you shouldn't have to worry at all about your son getting on and off transportation from the theme parks to the hotels.
And my best piece of advice - have a wonderful time! It may be a bit different than a typical trip, but there are memories to be made! Enjoy every moment!