Hypo/hyperthyroidism- is it possible to be on medication with hormone levels regulates and still feel symptoms such as fatigue and brain fog? or is it all in my head?

In general, no two people react to medication the same way. Often nit takes your Physician time to titrate the optimum dose for you. Also consider that you may have concurrent but unrelated imbalances. Has anyone suggested that you see a specialist Endocrinologist, especially as you seem to have an eccrine imbalance.

Once your thyroid supplement dose has brought the serum TSH & other thyroid parameters to normal, I would be hard pressed to ascribe those symptoms to your thyroid status. There are other causes of chronic fatigue such as sleep deprivation,anemia, chronic stress, depression,infection,chronic inflammation to name some. After a physical examination & testing, your MD can advise you best.

Agree with Dr. Colantino. There may be some other factor responsible for your symptoms. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!