There's literally no way she doesn't and its not my own bpd projecting and I'm dying to know if her therapist ever speaks about her diagnosis.  It's common for bpd patients to obsess or emotionally burnout their therapists which is what Gretchen does by stalking her therapist 

"You were a different person for everyone you met until there was no Gretchen left"
"Wed be best friends Monday and by Sunday you'd look right through me" 

She had a rough childhood, she uses drugs and drinks and has reckless sex, is a reckless driver, is extremely impulsive,  she's moody, is worried about being abandoned.. I mean really do I need to say anymore 