Somewhere in the back of my mind I seem to recall being told, by one of the various mental health professionals I've seen over the years, that one drawback of Seroquel is that it causes weight gain. (Please don't quote me on that one though. I could be wrong.) I've worked hard for years to keep my weight at the level it's presently at. And one of the things that keeps me from considering being on any kind of medication (psychiatric or otherwise) is concern over the potential for weight gain. The fatigue that can accompany taking antidepressants is also a big concern for me. So I can sympathize with your situation.

Here are links to 2 articles, from PC's archives, that talk about how to handle the overwhelming fatigue of depression. I don't know if they'll be of any help. But perhaps there's something in them that can be:

5 Tips for Dealing with the Overwhelming Fatigue of Depression

5 More Tips for Dealing with the Overwhelming Fatigue of Depression