It sounds like we have a similar story but my diagnosis is Bipolar. I would have depressive episodes, get treated for a while and then stop treatment because I felt better. When I felt better I would thoroughly enjoy studying and staying up all night to write papers. I accumulated two Masters degrees along the way.Eventually I was properly diagnosed with Bipolar and realized that when I felt "well" was simply a manic phase and almost as destructive as my depressive phases.

Now, however, my moods are stable and I am doing much better. I am also on an SSRI but I don't have the same risk for serotonin syndrome that you do. There are, however, other treatments available. I juts yesterday read about Lithium being used for treatment resistant depression. Of course, Lithium comes with its own side effects.

Either way, keep on seeking the right treatment and find someone good to work with to try different things. My psych nurse is wonderful and has led me through many med changes until we found something that works for me with minimum side effects.