Oooh, good point! Moods not making any sense in light of external events. That's a really important thing to remember in trying to tell them apart. For years my first severe and persistent depression confused me (didn't know I had BP). Everything was great. I was having a really good time. Then "wham!" out of nowhere, and it hit hard. And didn't let up for months. My world fell apart. It changed the course of my life in a major way.

Decades later, some are obvious to me and some it's harder to tell for absolutely certain.

I'll second that mood tracking is very useful. And that cyclothymia would not be as obvious, but worth keeping track of things (depending on how you feel about it of course) to see for yourself what goes on, how disruptive it is to your basic functioning in life and whether it's problematic to the point where help should be sought. Help meaning different things depending on your findings.

When you say "new physician", is it a GP or specialist of some kind?