First I just want to say that I think it's really great that you're taking the step towards therapy in favor of just medication. It also sounds like you have a really decent GP, as many wouldn't even make that type of recommendation-- they would just proceed to write a prescription.

I want to tell you that I hate online mental health quizzes. I believe that they can be really damaging for some people. Online quizzes ask you about certain symptoms and you have the opportunity to fill in a very cut and dry answer (yes, no, somewhat, often, etc.) The thing about mental illness and personality disorders in particular is that none of it is cut and dry. A lot of people possess charateristics of borderline personality disorder... then the quiz will tell you that you have it... What the quiz can't do is help you to recognize that every personality disorder and mood disorder exists on a continuum. It doesn't take into account social and environmental factors, interactions, etc. This will all unfold when you enter into therapy.

It's fine if you don't agree with your GPs assumptions. However, I am guessing from his assumptions that you are experiencing depression and anxiety-- and that's the key thing. When you go to therapy you don't want to be too concerned with telling your therapist what you think you have, rather, you want to tell him/her about what you are feeling/experiencing/how you are relating/functioning. That's what you'll be in therapy to work on-- Most therapists do not rely too much on diagnoses for therapeutic purposes... insurance purposes maybe, but a good therapist should not zone in on a particular diagnosis, rather he/she should be concerned with getting to know you and treating the whole person.

Good luck!