Boy, same here. I am technically self-employed, but I have committed 30 hrs/week to my favorite client. (So it's more like an employee again.) I go into the office 2-3 times each week. (Lucky!) They know of my disease and are very supportive, but I am constantly feeling like a flake. I do very good work and am conscientious about my hours. Even through they understand, I feel horrid when I don't make it there until later -- like 10:45 or so. I know I couldn't have done any better. But...
Also, Monday I had to send an email to tell them I just cannot travel. They've been requesting lately. My anxiety levels go through the roof. So, I finally said NO. They replied it was ok, but now I feel like I am not pulling my weight. Of course, I never said I would/could travel. (I can't leave my 10 year old alone anyway!!!) But I feel guilty!