I can completely relate to your post cause I have done the exact same thing my entire life. There was always a female teacher that I attached to through school, I am not sure why but I believe I used them to try and get what I had always longed for- "the perfect, loving mother". A particular high school teacher was my major obsession, I knew everything about her- like you I knew her car, license plate number, what she liked, and her family members/pets, I envisaged myself being her daughter and to a large extend she allowed this to occur. Unfortunately it went pear shaped when my clinging bothered her and she harshly abandoned me.
I find I go through a cycle system of clinging and then angrily retreating because my reality and their reality don't align the way I want it too. The hardest thing for me though is discovering what is real and what's not and coming to a sort of acceptance of this.

Whether it is BPD related or not I am not sure, but at least you are aware of it and have insight into what you are doing- that's the first step. But know that you are not alone
Hope that helps
Teddy