What are you doing about the low ferritin and low mchc? Are you taking B12, iron, copper, and folic acid supplements?
Tinnitus is especially linked with vitamin B12 deficiency. Perhaps you should consider getting some methylcobalamin injections, as vitamin B12 is often poorly absorbed. Magnesium deficiency and zinc deficiency may also be involved in tinnitus. Molybdenum supplements 500 mcg a day may help relieve your brain fog.
Eating a low carb diet and eating 5 or 6 small meals a day rather than 2 or 3 large ones will help relieve your hypoglycemia. Nuts and seeds are a great source of minerals, fiber, protein, and calories that is low carb(avoid cashews, pistachios and penuts though).