I started out with a BP-NOS diagnosis. It stayed that way for two years, until I was hospitalized for suicidal ideation and then the hospital pdoc diagnosed me with bipolar 1. I've since been seen by three more mental health professionals, all of whom agreed with that dx.

NOS really only means "we think you have thus-and-such, we just haven't figured out what flavor it is". Sometimes it takes literally years for the pros to put together a full explanation of one's symptoms. Regardless, the treatment for all types of bipolar is pretty much the same, and NOS can be just as big a problem as the others. Labels are basically used so insurance companies will pay for treatment, anyway.