I started out as bipolar 1 and it is worsening over time. This worsening effecting very common with bipolar. Sad but true. There are some theories as to why, one of which is called the kindling theory.

As far as I know a bipolar 2 diagnosis can turn into a bipolar 1 dx at any given time. All it takes is one manic episode. I know all that sounds discouraging and I myself have been hospitalized for mania/psychosis. And the episodes are indeed long lasting. But it can be overcome in the same ways as bipolar II. I would educate myself on delusions and other psychotic features just in case. It is a lot less scary with insight and knowledge.