Hi Nicky,

I've had a similar experience. I was misdiagnosed or undiagnosed for 13 years before coming to a diagnosis of BPD. I'm just 33, so I know for a fact that the BPD diagnosis existed 13 years ago.
Therapy has never worked for me, too. Nonetheless, I'm feeling better now than I was 10 years ago. But that's at the price of taking lots of meds. Psychotherapy simply doesn't work.
I've come to the conclusion that's because I'm not doing the right kind of therapy. I've done CBT for many years, now I'm doing MBCT, which is still a sort of CBT. It worked wonders for panic attacks and phobias (though not all phobias), but nothing for BPD. I am now considering DBT, although I'm not quite sure about it, because I would probably need to move in order to do it, as thay don't do it in my area.