I am not officially diagnosed with either one, but I believe I may have both. I have suspected that I am on the autism spectrum since 1997, and I'm pretty confident that I am, but I've only suspected I might have Borderline Personality in the past week, and it was suggested to me by someone close to me.
I've been going through a crisis in the past year that has been so harrowing emotionally that I have been struggling to understand how my emotions can be so extreme and so out of my control, and that's when my close person suggested it could be BPD. So at this point I don't know.
I don't know if that would be helpful to you, but you can contact me if you wish.