any chance you can change doctors? i had same problem, severe hypo, and was given levo--did not work. Tried several things, but ended up with Armour Thyroid extract (actually, use the generic) which has both T3 and T4--this helped, but not cured, the severe fatigue.
There is also a drug manufactured tht contains both t3 and t4.
with levo, often the t4 not converted as should be to t3 (esp if you have any liver problems).