"The sugar cravings are constant, they don't match up with when I'm hungry."

so that probably points to low serotonin rather than low blood sugar. Are you doing anything to try to boost your serotonin levels? I use licorice tea to do that. Others use St. John's Wort or 5 HTP.

"But I can't honestly see how mercury from 4 fillings and lots and lots of chelating afterward could still be making much of an impact now. "

You had only 4 amalgams? Did you eat plenty of tuna or other high mercury fish like swordfish? Perhaps your problem might not even be due to mercury, but perhaps lead, other heavy metals, or
else some other digestive or homonal problems?

Do you get enough vitamin D? Do you notice any pattern to how you feel at different seasons? Any other possible patterns? Have you tried rotation diets? Do you believe your drinking water is safe, and not loaded with heavy metals? Do you live near a coal powered electric plant or other major source of air pollution?
Are you sure you aren't exposing yourself to too much aluminum?
Many advise not to cook in aluminum pots or using aluminum foil, and not to take antacids with aluminum. Aluminum containing deoderants might also be a factor.

I am convinced that bread is also something that people should stop eating. It usually has bromine in it, is made with yeast, and has way too much carbohydrates.