Found disabled for SSDI on first appeal, but they want a Payee

I was found disabled on my first appeal (a rarity, I know). I have severe anxiety and paranoia...as well as a bit of Asperger's syndrome. I basically can't be around people for more than short periods of time without going into fight or flight mode. Social Security told me I have to have a Payee. I told them I am more than capable of handling my own money and do not trust others to do so. They asked me to come in for a meeting where they will ask me questions.

I have a lawyer, but he knew about this and neglected to tell me that my case was being held up for the last month by the whole Payee scenario. I suppose he was letting it go as far as possible, in order to get a larger chunk of my backpay. Fortunately, I called on my own after the lawyer seemed disingenuous.

My question is: If when going to the meeting I seem OK because I'm heavily medicated, can they reverse their decision because I seem calm enough to handle the world...even though I've already been approved? I'm assuming they don't have Doctors at the SSA office and can't do this. I'm very worried that something may go wrong.

Is there anything I need to know prior to going to this meeting? I'm afraid to ask my lawyer for advice, as he's been dishonest with me so far. I'm feeling very alone right now.

Thank you!