1st, I assume by BPD you mean borderline personality and not bipolar disorder.
I don't think telling her you think she has BPD is going to be the best idea. If anything, just barely suggest it. In other words, "I was reading this article about BPD and it reminded me a little bit of you...just thought I would mention it." Even this can backfire because she may take it as an insult if she's in denial that she is just fine.
The main treatment for BPD is psychotherapy and she doesn't sound too keen on that. One way to get her some help is by starting with a family therapist. This sends her the message "let's work on our relationship together" instead of "you have a problem...go fix yourself."
There is a great book you should read: Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder by Paul T. Mason and Randi Kreger . You may also want to consider finding support for youself; http://www.nami.org/ could help you find a local support group. No matter what professional advice I give you, it will be invaluable for you to hear how other parents' handled similar situations.
Good luck....let me know if you need more info.
If the doctor has a good relationship with her...and might have better luck encouraging her to see a therapist, then go for it. And if you just want some feedback from him for yourself, and trust that he won't say anything to her, go for it. Otherwise, there's not much to gain...it's not as if he can offer her any other treatment for it. Is there a particular outcome you're hoping for by taking to the primary doctor?
People with BPD often have substance abuse; and stimulants can increase behavior problems in someone who truly doesn't have ADD. Now that you've told me that, I think it's important that you do consider telling the doctor.
Now, if he listens to you and stops the adderall, this will obviously make her very mad at you. And I can't say from here that she doesn't have both BPD and ADD...so I don't want to recommend stopping it immediately. Many GPs make patients see a psychiatrist to confirm diagnosis when they are prescribing stimulants...he could basically make her do that if she wants the medication continued. This could upset her...and I don't know if she's the type who would just go find another GP...sadly, it's not hard for people to find docs to prescribe whatever they want.
But remember, you shouldn't avoid telling the doc just b/c it will make her mad. Tough love is important...even if she doesn't understand it at the moment.
However, he could also potentially just listen to your concerns and note them. Then down the road if there seems to be problems with the adderall...he can reconsider whether to prescribe them. Perhaps you can also remind him to tell her that the best treatment for depression is meds with counseling and that she should do it...not just "if she thinks she needs it." I like telling patients that psychotherapy/counseling has been proven to work by studies using sophisticated brain scans. It may be more "palatable" for her to think she needs counseling for depression...rather than BPD...
I hope this is helpful...anything else I can answer?