It does sound like just BP2 I'd say, indeed. But I wouldn't know for sure since I don't have it. I do remember the time my mania wasn't severe, which could be described as hypomania. I also had a period of what you could call hypomania, sleeping 5 hours a night for months, when I was commuting to work and there was a lot of people around to stabilise me. It ended in mild depression and mania and congruent psychosis, severe depression and more severe mania and incongruent psychosis. The last phase was very short compared to the previous two periods, but the period of hypomania was longer than that of mild depression.

I am mostly depressed as well, but it's more very mildly, borderline psychotic and negative symptoms of (disorganised) schizomania.

But I think most people with BP are mostly depressed. Severe mania requires more time to recover than the mania itself lasts. That said, another manic episode may happen rather quickly afterwards or a mixed episode/state may immediately follow the mania.

If the "hypomania" is very short-lived during a depression it may "just" be part of an atypical depression.

It's instability no matter how you call it. More or less stimulation can be used to stabilise it if it's not too severe. If it's more psychotic it may be impossible to do this. If it's BPD you may hurt yourself by destabilising.