Well, therapy might help with that - still difficult if you're very shy or have social anxiety, but you can build up a relationship over time that might help you learn better skills for situations like that. A lot of us feel like we're faking although we're not (we just don't really know what normal is like and therefore assume what we experience is normal) and it's not unusual for people with mental illnesses or other brain disorders to question their diagnosis and disbelieve it, even in the face of overwhelming evidence to the contrary.

Another strategy that could help is to write down what you need to tell your docs before you go. Then if you get all tongue-tied, you have a prompt to help you get the right message across. I do this because I often forget something that I know is important to talk about. And I've seen people on PC recommending printing out your own posts to take to a doctor or therapist, because sometimes we're better at expressing ourselves here than we are at the office. You could even just hand them a list of your symptoms and let that start the conversation, rather than trying to start by saying something that's hard for you to express.