they need to get to know you in order to make a true diagnosis. bpd is tricky and tends to present itself in different ways. in canada, depending on the severity of the situation, it takes about a year or two, and they won't diagnose anyone under 18 unless it is very obvious. my psychologist told me she thought i had bp when i was 17 but i only got the official diagnosis a year later. i had to sit in a room with about 6 doctors who read my file out loud and asked me alot of questions. it was hell.