I am not one that will be able to give sound advice, Faraway, because stability doesn't last long for me yet, and I've been fighting this battle for several years. When the meds finally kick in I only seem to have a period of a couple of months before I need to seek another change, although I did last with Cymbalta for five years! The only thing with that drug is that was miserable when coming off of it.
Lately, I tend to go into hypo mode when my meds aren't right, so at first I enjoy it. This is where I am now. The only thing about this state is that I mess with my drugs and I go back to old, abusive habits, so yes, I can relate to not having stability with both ends of the mood spectrum.

If the meds don't kick in after six weeks, you might want to visit your dr. soon to get an adjustment. There are many combinations that can be offered.
Good luck!