Mental health diagnosis isn't an exact science. And we also change from one part of our lives to the next, so the areas that we struggle with do tend to shift around.

ADHD in childhood often predicts that you are likely to have other struggles as you mature, ranging from personality disorders to depression to substance abuse and addictive behaviors, etc. And, also, ADHD has been over-diagnosed and used as a catch-all for kids who stand out in one way or another. Bipolar disorder has become "the new ADHD" in recent years, as it has been diagnosed more and more, not always appropriately.

I have had several dx too. Didn't get any therapy until after I had left home, although I know I was depressed throughout childhood. The first therapist I went to told me that I was just homesick (I know I was severly depressed and had no social skills). The next one diagnosed dependent and avoidant personality disorders. Not all of them gave me a dx, but I was in treatment eventually for depression several times. Also dysthymic disorder, social anxiety, generalized anxiety disorder. BPD fits, but never got put down on paper. Ultimately, it doesn't matter what the dx is so much as that you get treatment that helps with what you struggle with.