A new diagnosis can cause a tailspin, for sure.
If/when you accept the diagnosis, you may have periods of wondering if it's correct, while also settling into life with it.
I have several diagnoses, as I have autoimmune illnesses. The BP-2 diagnosis came much later and after a lot of suffering with long, paralyzing, atypical depressions. My hypomania and mixed episodes had started during recovery from a traumatic brain injury. Since BP-2 treatment has helped, I am relieved to have the diagnosis. (I recall stress-induced hypo when I was much younger. It had then disappeared for years. My longest psych DX is c-PTSD).
When we suspect a BP Dx for awhile, even years, it's less of a surprise; yet, the confirmation might cause a bit of an adjustment reaction.

WC