I don't know which candida diet you're following, but a lot of people don't follow the truly strict one. The truly strict one is what caused most of my symptoms to go away within a few days.
I went on vacation for 2 weeks recently and needed to break my diet every day. I didn't have any severe reactions, but, after 2 weeks, my fiance told me it seemed like I had gained some weight in my belly. I returned home and began the diet again, and the extra belly weight disappeared overnight.
I think you are right. Chelating would likely help the most with your belly fat issue. It will take time though.