I agree that your primary practitioner did not do anything wrong by underprescribing, as more advanced psychiatry is out of the scope of their practice.

C-PTSD covers all of the borderline criteria, so it's not really different although those with certain symptoms may be more prone to getting the actual BPD diagnosis from some. And I think your therapist was trying to protect you from the negative stigma, though perhaps she should have brought up BPD. It doesn't sound like she meant to betray you. I do think they should be honest and upfront.

Although it is true that diagnosis is a matter of opinion more than science and does not necessarily represent what a client truly has, however, I don't think the psychiatrist has any business putting a personality disorder in your record. That can have really harmful consequences and follows you the rest of your life. I think they should discuss it with clients, but they better damn have a good reason to label you by including that in your record. He's the one I'd be angry with-not my GP or therapist.