Ok, for one thing, having a personality disorder does not equate to being a psychopath. If you were diagnosed at 16, the diagnose can't be antisocial personality disorder because that one is not diagnosable prior to at least age 18, and that is the one that corresponds to what we think of as psychopathy. The other personality disorders could be diagnosed at 16, but with caution because teenagers are still developing their personalities and because the symptoms of some personality disorders are actually fairly normal for teenagers and you can grow out of it. So, a personality diagnosis at 16 is by no means permanent or definitive. It also doesn't mean a lot to say that someone has a personality disorder without specifying which one, or the traits that are relevant, because they are all so different.

It is possible to have a personality disorder and bipolar or other mental health disorders. Bipolar disorder usually consists of acute symptoms that occur during episodes and when not having an episode, most of the symptoms may disappear. Personality disorders are longstanding patterns of behavior that are learned during childhood, often early, and generally are adaptive to the conditions that you grew up in but become disorders when you are an adult and those behaviors no longer fit your circumstances but it is difficult to change what you have learned and done for your whole life. For a lot of people with bipolar disorder, they may have remissions from the bipolar disorder symptoms and it is when those symptoms are under control that the personality disorder shows up.