Hi, A lot of people have suggested B12. This will only help if in fact you are anemic.If you aren't, it won't really help the fatigue. See http://www.baptisteast.com/recipes/boosting.cfm or google "B12 fatigue". I would suggest getting a blood test for anemia if you haven't already.
I used to have really bad fatigue until I got my iron levels up. However I still don't feel I'm at a normal level in terms of being tired all the time. And I too sleep up to 12 hours solid good sleep a night!
I'll be reading all of these replies/suggestions for sure. Goodluck, Kat