You are so right CaptK, such drastic shifts of goal posts can be soul-destroying. I have been wondering why this might be and I've come up with 2 or 3 possible explanations.
Of course, rapid mind changing, as part of "Splitting", makes perfect sense. Also, due to there being little or no real sense of identity, people with PD are more partial to changing their mind and, lastly, perhaps the chronic emptiness trait is temporarily filled with optimistic plans, until it gets bored.
The article I was just reading, describes people with BPD as "Chameleons"; perhaps we feel inspired by another person's attributes but that notion soon wears off once someone/something comes into the limelight.
It's understandable to question any diagnosis and even better to discuss this further with the Pdoc. When I was diagnosed with BPD, I had never heard of it. It was the same with Agoraphobia, I thought they were talking about someone else. I'm sure, after meeting with you again, the Pdoc will be able to reach a more accurate diagnosis