Welcome...I'm a little late responding to your original post, so I hope you continue to read what we late-comers have to say.
I was dx'd w/personality disorder NOS (not otherwise specified) w/avoidant features last summer and started psychodynamic psychotherapy. I've seen a couple of Ts in the past, but there was something about this T that made me want to give therapy another try. I struggle w/what's written in the research articles and what I believe. So, it's a bit up to you and also your T as to whether or not you can change.
First, my T has been in private practice for 36 years...lots of experience w/lots of different problems. Secondly, I'm older. When I was in therapy in my 20s and 30s, my issues were different and I wasn't so invested in changing (something I don't think researchers takes into consideration when they plan their research). Thirdly, therapy, done correctly, is hard. Building a relationship w/your T, learning to trust your T, understanding that the therapy is really ALL about your relationship w/your T is difficult for most everyone. The relationship w/your T plays out in exactly the way you relate to others in the world. Using your relationship w/your T to change how you relate to friends and family is the ultimate goal. Trusting your T to show you ways to change how you interact is crucial.
I believe you can change aspects of your personality so that you become happier, more satisfied w/your life, and a better friend to others. Finding the right T is not an easy process, either, but if you like the T you're seeing, tell him/her what you want to gain from therapy and see if s/he is able to get you to the finish line.
I wish you the best and hope you take the chance to find a way to make changes!!