Hi tdog
I am very sorry you are going through this. Your mother sounds like quite a difficult person to be around. I do think it's great that you have the support of a therapist as you deal with all of this. Having a solid support network can really be invaluable.
I also think it's great that you've taken this step to reach out here for more support. Unfortunately, this site does require the members to be at least 18 years old. There are also other resources though that can be helpful to you, I've listed some:
Teen HelpYour Life Your Voice1-800-448-3000
Dealing with a BPD mother can be very challenging indeed. When it comes to BPD, knowledge truly is power though in my experience. Now that you likely know what you are dealing with, you can educate yourself about the disorder and the strategies to effectively deal with your mother.
Take care and know that once you turn 18, this site will be here for you to get more support
The Board Parrot