I would consult with a nutritionist to ensure you are not pushing your body into starvation mode, as tctrek suggests, which will affect your metabolism in ways that don't show up ion a TSH test. It you are doing 3 hours a day of aerobic exercise, you need to fuel your body appropriately. Talk to your doctor about nutrition as an alternative to drugs. Mastering the nutrition piece is also something you can/should do your whole life - as opposed to amphetamines.