Hi, Laura ~
I'm sorry to learn of your post-op struggles. I had a 4.5 cm AN debulked then radiated and like you, I experienced some fatigue afterward. Fortunately, I was retired at the time of my surgery and didn't have to deal with work issues, as you do. In most cases, the fatigue resolves as your body gets stronger - but that is not a guarantee. In the months immediately post-op, I attributed some of my noticeable loss of stamina to age (I was 63), but I have to assume that with the brain working hard to compensate for my SSD and loss of one vestibular nerve as well as the trauma of major surgery, there wasn't a whole lot of physical reserves to spare. This is likely what's happening in your case. It is certainly not uncommon.
Jan's suggestion about applying for Social Security disability benefits is sound but it can be an arduous process. I know this because my wife went through it (successfully) in 1996, when it was actually a bit less difficult to be 'awarded' disability benefits. She had to retain an attorney specializing in Social Security law and, specifically, in obtaining disability benefits. Fortunately, he worked on a contingency basis and she paid very little to him 'out of pocket'. If working is proving difficult and impeding your recovery, you should look into applying for Social Security disability benefits. However, this is a decision only you can make.
Jim