It depends on the therapist. I'm always trying to diagnose myself, and I have lots of internet test results, and my T does not want to hear it. But when you are just starting therapy, if take in your results and talk about it, but don't approach it as "here's my diagnosis," I think most therapists would be open to at least talking about it. Be careful about going overboard. Being a "quiz junkie" isn't as helpful after a point, because it really is looking an external source to learn about your inner self. Just looking inward at yourself and talking about your own thoughts and feelings and concerns is a lot more real and genuine. One of your concerns might be that you see a resemblance between yourself and BPD. You can talk about that. But don't present it as your diagnosis. Let the therapist decide about that.