You might want to cross post on the disABILITIES! board. There are many of us over there with multiple food allergies/intollerances.
One of my girls can't have gluten, milk, eggs, yeast, citrus or MSG. My other girl can't have milk, citrus, hazelnuts, brazilnuts, peanuts, blueberries, cranberries or sesame. We eat VERY well at Disney. The chefs at Disney are AMAZING at handling all kinds of food allergies.
What allergies are you dealing with? I can help give you an idea of some types of options you'll have, though you'll want to contact the Special Diets department to get the most up to date lists of safe foods and locations where they can be found.
Special Diets always has the chef from my resort call me at home ahead of my trip. The chefs at the resorts always come up with some amazing foods for my girls. This past trip, one of my girls ate pizza every day. They custom made it for them because the standard gluten free crust wasn't safe and we required soy cheese and the chef knew the vegan slices they use wouldn't work well on pizzas so they special ordered really good stuff. Since none of the allergy baked goods are safe for my 12 year old, they special baked up a large batch of brownies just for them. We also had chefs from several of our TS ADRs call us to discuss likes and dislikes and the details of our allergies.
WDW is the best place in the world to travel with food allergies.