No don't hold out. It's too important.
As I said, it can be very complicated at times, because we're so used to being poorly diagnosed.
But your symptoms are extreme and getting to be a threat to maybe even life and family. So look at the situation as having both POIS AND bi-polar disease. Don't feel bad about it. This is a problem that can't be controlled with herbs, or meditation or common sense, it needs medical treatment.
If you can resolve the bi-polar disease, you may not be cured of POIS, but you should feel a lot more stable.
There's no reason we can't have both problems, and NOT to treat true depression or bi-polar problems with proper pharmaceuticals is extremely dangerous!
Put POIS aside for a little, treat this first, it HAS to help, and then you will be in a better position to isolate and work on your more specific POIS problems.