It’s difficult to know if you have borderline personality disorder. To answer your question directly you should absolutely talk to your psychologist about the information you’ve shared in your letter. It’s important that he or she know about the problematic relationships you have with others. It’s also important for your psychologist to know that you feel you don’t have an identity and that there are occasions when you engage in self-harm and have suicidal thoughts. This information is critical to share because what you have described is serious and your symptoms need to be addressed immediately.
I’m also wondering about the fact that you’ve been in therapy since December of 2007 and have not shared this information with your psychologist. Perhaps you were not in outpatient counseling with the same psychologist and that could explain why you have not shared this information. I’m speculating but it also could have been that you’ve been focused on other issues in therapy related to anorexia and OCD and that’s the reason you have not mentioned it.
Knowing whether or not you have borderline personality disorder is not as important as treating the symptoms you’ve described. The inability to have appropriate or healthy relationships will make it difficult to have and keep friends. The obvious issues with self-harm are that it’s not only psychologically harmful but physically dangerous. There are other ways to deal with stress and negative thoughts and feelings that don’t involve you physically harming yourself.
I sincerely hope that you will begin a dialogue about these issues with your psychologist. If he or she knows that you are having negative thoughts or feelings then the both of you can begin to address them in counseling. That is what needs to happen. I hope I answered your questions. Thank you for writing.