Here we are, more than 3 years since I started this thread (wow) so I thought I'd update again.
I've been off Valcyte for about a year and half. I continue to improve with additional treatments. There's been no apparent return of HHV-6 or related symptoms. Daughter has been off Valcyte for more than 2 years and also has had no return of HHV-6 or related symptoms.
Since I stopped Valcyte, I took Equilibrant for a while to deal with Parvo B-19 and Coxsackie. Both resolved in several months. I felt better after that. It wasn't huge, but noticeable and definitely worth doing.
Discovering and treating OI has improved my functionality and cognition. It wasn't as big an improvement in my condition as I got with Valcyte, but significant nonetheless.
These days I tutor 20 hours a week, 15 of them away from home. I drive, and I walk into small stores like pharmacies or convenience stores on my own. For longer distances I still need to wheelchair to avoid PEM. I no longer need to nap during the day and am not abnormally tired by the end of the day. I can do normal housework if I pace it carefully. My biggest problem now is limited energy/PEM. I've increased what I can do a lot, but I'm still significantly impaired. I wouldn't call myself fully housebound at this point, but I really can't get out and about much by myself because I can't walk very far without causing PEM.
When I think back to the time when we'd just started Valcyte (3 and a half years ago), I'm impressed with my daughter's improvement, and mine also, although I have a long way to go still. Back then I was bedbound, felt crappy all the time, and had major cognitive impairment. Daughter and I had to take turns lying down in the back of the van when my husband drove us to see Dr Lerner because neither of us could sit upright or stay awake for the 6 hour trip. We spent our hotel time in bed and still had minor relapses from the trip. By the end of our Valcyte treatment, we were both up and perky (!!) the whole trip. Last year daughter drove herself for the same 6 hour trip to see her boyfriend about once a month. She graduated from college and is now in graduate school. She's done several day hiking trips in the mountains. What a difference!
I know that a healthy person would feel extremely unhappy to be limited in the way I am now, but for me it's such a big improvement over where I was 3.5 years ago that I'm quite happy to be where I am now. That isn't to say that I don't want to be better or that I'm not continuing to look for ways to improve.