How cool that you have been able to commit so fully to your practice! My first guess as to why you might be experiencing fatigue is simple dehydration. The first sign is sleepiness after your practice, and it progresses from there. When I was in teacher training, we had two 90-min Fires per day (6:30a & 6:30p), and one Wood class at 11am. After the first week, I bottomed out completely, and found a good hydration regimen for myself that worked well for the remaining seven weeks: I would drink one "Smart Water" during each 90-min Fire, and one electrolyte packet after each. You probably would not have to do as much electrolyte as 2-4/day, but if you incorporated either one Smart water and/or one electrolyte packet (less sugar than Gatorade), daily, it might help your fatigue. Let us know if you've already done this, and we'll discuss more!
Good luck! You're well on your way to the 60-day Challenge!