*hugs* I googled Celiac's disease (Wikipedia); I know that one, a woman from work has this. Don't worry, you'll live - means: You can get a pizza that is gluten free.
There is a special flour that you could use for recipes like your onions. My friend from work took the dough to the pizzeria and they made her a pizza she could eat. :)
Good luck, hon. *hugs again*