I've been diagnosed with BPD but I believe I might have AvPD as well (or maybe traits?). My T doesn't, but I think people don't understand AvPD. Actually I wish I didn't have it and wish he was right but I'm afraid he is not. Even though I seem relatively social, but there is this constant feeling of inadequacy, of shame, hard to describe. Sure, it can be present in BPD too, I don't know. I've been afraid to live, been living in my head, have all these fantasies of a life I'll possibly never have. Also very afraid of being embarrassed and ridiculed and do everything to avoid that...I hate that.
I've read that BPD and AvPD often coexist.