Hi allabout, I was diagnosed after 13 weeks of intensive therapy and personality testing(sorry, can't remember the name of the tests) with a psychologist and a psychiatrist through my local public hospital. This is the same hospital that I had my psychiatric admissions so I was observed very closely. I had many years of cognitive behavioural therapy with my wonderful psychologist who put up with my rage and constantly walking out and abusing her. Many kudos to her. Most good therapists look at a variety of common features of pds and apply it over time to the client presenting(childhood, schemas, values). DSM, the bible of psychiatry has a comprehensive list of pd;s and symptoms are often compared to that. But u r right. PD diagnosing is difficult especially bpd as it mirrors a range of other disorders. In the last year I have been diagnosed bipolar as well so you could say that I always had it and bpd masked it. But my psychiatrist took 4 months to come this conclusion. I was put on lithium by my GP 12 months ago after a hospital admission who swears that I have had bipolar for years. But I didn't listen. I have since found out he was right. Sometimes the treatment will diagnose you. I hope that answers your question to a degree and thanks for kind words. Its nice to hear it.
P.s. Psychopathic pathology is not always part of a pd. Rage can be but I presented with more psychopathic tendencies. I was homicidal towards pretty much everyone. Forgive me if I generalise, but pd rage is usually directed, no less potent though. Just wanted to clear that up.