Hello JustMelancholy: I'm sorry you are in this most difficult situation.

From my perspective, I think the short answer here is to take someone with you who can act as a support person / advocate. Beyond that I don't really know.

I do know how intimidating doctors can be. It can be really tough when you're in there alone.
Is there any possibility of getting a letter from your previous pdoc outlining what has worked for you & supporting the idea of keeping you on the same med regimen? Such a letter could possibly be faxed to the new pdoc with a copy mailed (or e-mailed) to you.
I see this is your first post here on PC. So... welcome to PsychCentral… from the Skeezyks!

I hope you find the time you spend here to be of benefit.
PsychCentral is a great place to get information as well as support for mental health issues. There are many knowledgeable & caring members here. The more you post, & reply to other members’ posts, the more a part of the community you will become. Plus there are social groups you can join & chat rooms where you’ll be able to connect with other PC members in real time (once your first 5 posts have been reviewed & approved.) Lots of great stuff! So please keep posting!