all pdocs are confident of their diagnosis though i am sure they are all bloody ignorant themselves. psychiatry is a new discipline that dates from a century ago only so don't expect they know everything.
however whether BPD or BP the meds are the same almost, so you are not losing much by a wrong diagnosis. I bet No ONE knows anything about BP except that a person havng extreme mood swings, that mania appeared on the radar screen from time to time and that mood stabilizers work sometimes and that antidepressants are dangerous but indispensible. This is how they define BP. From there on they give you this or that until you stabilize, if your case is mild your continue if not you fluctuate to find a better ms and so on then you are diasapointed and write to medhelp possibly someone else had the same experience. this is the story of the majority of us. if you don't post anymore it means you are ok and you don't need help until the meds stop functioning etc...
my experience forget about wanting to be normal completely and adjust your life according to your mood and keep going. God doesn't forget his creatures and it never deteriorate like many say, it only fluctuates, one day you are in your worst so you feel BP is striking hard and another day you feel the best. Nothing will happen more than yhis. So don't fidle much with your drugs, the more you take drugs the more it affects the brain.
however seek your new pdoc and see what he says
The best way is to note down all your symptoms and problems on a paper and show that to your psychiatrist and he will surely understand.All the best.