While “The warning signs” might be obvious to you, they can be easily misunderstood. This can lead to a shadchan labeling someone as psycho when they were just having a bad day. Rather than labeling someone based on flimsy evidence, I suggest waiting until after the third date and then paying for professional advice.
At that point – before the engagement – there is no issur of lashon hara, so it is the ideal time to try to find out the truth.
The three conditions that you mentioned, Asperger Syndrome, Borderline Personality Disorder and Narcissism, are not well-defined. We could sum them all up as problems creating close relationships. I think the best approach is to ask about the roommates and friends of the prospective shidduch. On the dates, it is a good idea to ask about friends and roommates as well as family members. Ask about sibling rivalry. Ask if they enjoy spending time with their father. Ask for stories from their childhood. After the third date, I suggest the couple go on a long date (meaning from the morning until night begins). It’s hard to fake being nice all day if you have one of those conditions. Then go home and ask yourself if you want your vacations to be like that long date.
AT THAT POINT, Don’t be afraid to go to a professional marriage counselor with experience and present the evidence. Most Rabbis and Shadchanim are not professional marriage counselors. It can be very difficult to distinguish between an immature girl and a narcissistic girl. The professional should give you one technique specific to that one individual to help you test whether you should continue the shidduch or not.
And of course, don’t forget to daven.