Hi Theresa!
I'm sure traveling will take you out of your comfort zone but don't worry, Disney is an awesome place to travel with special needs children.
Being out of their element can be stressful for some autistic children. You may want to request a corner ground floor room at your resort. That way if one of your kids becomes too anxious, you won't stress out feeling like you're disturbing other guests. Since you've already booked, call your resort & explain your situation.
I've found that staying at a resort convenient to the parks helps in case we need to take a break. The resorts along the Monorail line are great for this as are the resorts near Epcot & Disney's Hollywood Studios (i.e., Yacht & Beach Club, Boardwalk).
Click
here for info regarding obtaining a Guest Assistance Card.
Talk to your kids about the trip. Show them pictures or videos of Disney World & characters so that they become familiar with them.
The parks are full of different types of stimulation. I'd plan for a break during the day & return later. You know your kids better than anyone so if they have any things that may trigger anxiety for them, avoid those attractions (i.e., attractions that are dark, loud noises, etc). If you have questions about any specific attractions let me know. If your kids have any comfort items, bring them if possible. If they have head phones or ear plugs to help keep the noise level down, bring them. If they become anxious, remember to relax & breathe & remove them from the situation until they calm down. If you see they've had enough, pack it up & head back to your resort. You may not get to do everything on this trip but you can make the most of everything you do.
Wishing you magical memories :-) Allison