Hi Twix,
Welcome and hello

Communicating with someone who has BPD is not intuitive, it takes some special communication skills.
Do you feel comfortable sharing an example of how a typical conversation might go? Sometimes it really does come down to how things are phrased.
Does she accept she has BPD? Is she open to getting treatment?
My SO's D19 was diagnosed bipolar with psychotic depression at 16. She meets most of the criteria for BPD, and I suspect they were of the mindset that she had to be 18 to diagnose. She is also away at college. How is your daughter managing? What are her strengths? How do her BPD symptoms manifest?
Glad you found the site. We're here to walk with you

LnL