Apologies for not having read all of the posts on this topic. The original poster confused self-diagnosis with a case in with she tried to diagnose someone else (her mother). The latter is a sort of do-it-yourself psychiatric assessment. In my view, self-diagnosis has greater credibility, with the exception of cases where there may be a factitious disorder, provided the individual is well-informed about the diagnostic criteria. They have all of the information which a psychiatrist would have to work hard to obtain.
The best way to make a diagnosis is to look at the diagnostic criteria and think carefully about whether they really apply to you. You must look at the general criteria for personality disorders as well as the criteria for each personality type. Be sure to go on the exact wordings taken from the official DSM or ICD publications, not a summary or interpretation.
It is important to consider a wide range of possibilities, not just the first one you come accross. Having got a "lead" into the issue, perhaps from a radio programme or something you've heard, broaden your search out to try to take in all the possibilities, considering the relevant factors in your life.
In the realm of personality disorders, several types of personality are likely to be somewhat applicable, but there is usually one primary type of disorder (see www.millon.net
). You must be able to rule out certain diagnoses, despite finding some of the characteristics somewhat applicable or useful. Many people have a deep sense of recognition on reading the diagnostic criteria and further descriptions of the disorder which applies to them. Some people may have a less typical pattern of dysfunction.
Online tests tend to over-diagnose disorders for the simple reason that they are usually made available in order to sell products such as therapy or further diagnostic tools over the internet. I've learnt from postings on this topic that there is an issue about entitlement to treatment on medical insurance in the US. I think this politicisation of the issue is unfortunate.