Try not to stress. I have never seen a company that is so thorough with dietary needs. Any restaurant we have been to for table service has provided our daughter with her own meal made in a separate area. Be sure to visit blogs for ideas for QS. If you can plan to go to a spot that you know can cater, then you will not have a very long wait. We would circle the restaurants we could go to on the map of the park so that we knew our options near by when we got hungry. I would also recommend trying to grab lunch on the earlier side, around 11 am. It will mean that you can see a cast member sooner and not have as long of a wait for your meal. Here are some of our go to sites
http://www.allergyfreemouse.com/dining/gluten-free-at-walt-disney-world-parks/
http://www.glutenfreedairyfreewdw.com
http://www.glutenista.com/walt-disney-world-gluten-free.html
My biggest tip is to pack some snacks along in your suitcase for parks. We find having snacks that are safe for DD on hand is easier than trying to find a place quick that might have a treat that will work.
Our favourite QS spot at MK is Cosmic Rays- we have always had such great luck with their special diets team.
Some of our fave sit downs are Tuskers at AK and 1900 Park Fare at the Floridian
I would avoid Hollywood and Dine at HS- they simply bring you around the buffet and show you safe foods, where as other sit downs will always make her a meal