Hello,
It is said that BPD shows up in your late teens or early 20's. I am like you in that I knew, or seemed to know myself when I was younger. I had a close friend in high school, was pretty outgoing, and I knew what I wanted to study in college. My trouble also started when I got a boyfriend at age 17, and got worse from then on. I was never that person again
I'm sorry you are having such a hard time Hang in there...Hugs