Thank you so much for your very helpful responses. For whatever reason, the information I read on Bipolar-NOS being sub-threshold alarmed me. I think I'm just looking for validation that my struggles really and truly are struggles. But your explanation that Bipolar-NOS can be sort of a precursor to official Bipolar I or II diagnosis makes sense. My psychiatrist did mention in our first appointment that she was still noodling over where to place me.

I did reach out to my psychiatrist because I was concerned. Here is her reply:

Good question, more when we sit together.
Briefly, the DSM diagnoses are limited in their foundations and utility. The origin was for record keeping and billing type purposes! So "NOS" becomes the catch all category for things that are clearly cyclical and biological in pattern but that do not meet the established criteria for the mail diagnosis. It does not imply anything about the distress or dysfunction associated with the diagnosis. Some diagnoses have "severity qualifiers" to better capture disruption.

Does this response reflect your personal understanding?