We can't really diagnose you here because we are just patients. It sounds like you may have some characteristics of bipolar---but so do lots of people who don't have it.

Since you've had trouble getting a diagnosis is there any chance of going to a really good dr who specializes in mood disorders? I was very hard to diagnose and wound up first diagnosing myself and then getting into a mood disorders program where they did a really thorough assessment before diagnosing me. I then got 6 free months of treatment from these great doctors while I did a clinical trial (which is optional). If there isn't a mood disorder clinic nearby a large teaching hospital will have psychiatrists who are experts in mood disorders and may be able to help you find answers. It's worth driving a little bit, even if you only go long enough to get a diagnosis you feel comfortable with.

Diagnosis is tricky. There are so many disorders that overlap and it take someone really good at diagnosis sometimes to sort it out.

Bipolar is also considered a spectrum disorder so you can fall in many places on the range which also makes it hard to really get diagnosed.

I do think that it is pretty normal to be more confident in some areas of life and not at all confident in others. I was very confident in myself as a professional but not confident at all in myself in friendships/family interactions, for example.