http://www.hsperson.com/pages/test.htm
I fit all the traits to the nth degree. If 20% of the population supposedly fit the minimum criteria I'd say I'm in the 99th percentile when it comes to sensitivity, probably 99.7 percentile for a male. Tests show that I have an unusually fast startle reflex. From the ages of 0-3 my parents couldn't take me anywhere there was music playing or loud background noise or I would cry the entire time. At age 5 I was diagnosed with PDD-NOS (related to autism, but high functioning) and ADHD. I've also suffered from dysthymia and on-and-off major depression since the age of 15. I also have some bipolar tendencies but they tend to be of the rapid-cycling variety with brief but very deep depressive periods accompanied by extreme irritability.
I have a mix of avoidant and borderline personality traits but my therapist doesn't think a diagnosis of a personality disorder is really warranted because I don't fit in a neat box. It seems like I've developed these traits as a coping mechanisms due to my sensitivity. The more impulsive borderlinish stuff I do only really comes out when I'm with people I'm very comfortable with, family and some friends I hung out with during my undergraduate years. I've been a loner most of my life though and don't do impulsive things on my own except when I go into an extreme depression and have these building and climaxing rage episodes triggered by depression.
Anyways, just felt like sharing. I don't know if there are other people here who believe they developed traits as a coping response to being a "Highly Sensitive Person" who feels vulnerable because they struggle socially.