Hi Erecura. If (and I say if) you have bipolar disorder, my best guess, as a person with bipolar disorder type 1, is to say you have likely never experienced full blown mania. At most, hypomania, which would only allow for bipolar spectrum diagnoses of bipolar type 2 or Cyclothymia, or the like.

Indeed none of us, including me, are qualified to diagnose. If you want a second opinion, I strongly suggest consulting with another psychiatrist or with a psychologist. Another suggestion is to not just go to a couple and then quit appointments, unless the professional ends treatment. Allowing a mental health professional to observe you over a longer period of time helps them make the best diagnosis. You can't imagine how many of us waited years for a proper diagnosis because we went to doctors "as needed", usually only when we were depressed.

I guess I can understand a mental health professional leaning towards borderline personality disorder, if you have a history of self-harm and eating disorders. It's not that people with bipolar disorder can't have these co-occurring issues, but much less often than people with borderline personality disorder. What other symptoms have made the doctor(s) suspect borderline personality disorder? If you don't know, you should ask.

You might consider mood tracking with daily journaling. Such practices can provide a lot of helpful information. Do certain mood shifts tend to happen in a regular pattern? If so, what things are happening at those times (stress, menstrual period, etc.)? Describe the stress/trigger. Do you have mood shifts throughout the day? What are their characteristics?

You describe yourself when seemingly depressed and when you feel you might have elevated mood. What are your baseline mood and desires? That can help determine if your "ups" are maybe really just your norm. There are many people on this earth who do not have a diagnosable disorder that are hyperthymic positive people.