My mom has Celiac, and I know that she feels 100000 x better now that she has cut gluten out of her diet. Her mood is better. Her health is better. She actually says that it's easy to stay away from gluten, knowing how crappy it makes her feel.
Unfortunately, unless the school has a salad bar and you've got a salad-loving 6 year old, I see a lot of packed lunches in your future. You just can't trust that there will be no gluten in a school lunch - it hides everywhere. Soups, sauces, dressings... And, unfortunately, once she goes off of gluten (after all the testing is accomplished) the slightest little bit will make her sick. Really sick.
Noodles restaurant does have a gluten-free rice noodle if you ask for it. Also, Chipotle is a great place to get Gfree meals out. Look into Bento lunches and see if you can't get some cute ideas for lunches that aren't centered around a sandwich. They don't actually have to be THAT intricate. No one expects you to make Hello Kitty rice patties every day, unless that's what you're into.
Keep trying various products - especially mixes for things you make fresh. I can't tell the difference between Mom's pancakes and "real" pancakes, for example. The good news is that Celiac is becoming more common, and there are a lot more products out there than there were a year ago, or five years ago.
Good luck!
A. @ http://prettybabies.blogspot.com