I have POTS as well as neurogenic orthostatic hypotension and autonomic failure if you ever want to talk more about it. You want to avoid anything that lists orthostatic hypotension as a possible side effect (some of the SSRIs, trazodone, remeron, the atypical antipsychotics, most of the TCAs etc).
This is going way back to pharmacology in med school, but I believe trazodone bind more preferentially to the alpha adrenergic sites than does remeron. Not positive. They both have alpha adrenergic properties.
I don't know what treatment you're doing for your POTS. For my various autonomic dysfunctions, I'm on droxidopa, midodrine, florinef, use compression stockings, have elevated the head of my bed, stand up veeerry sllooowwwllly and get every other day IV saline infusions. All of this has more or less stopped the almost daily fainting episodes I was having and I'm asymptomatic a lot of the time and am able to do pretty much whatever I want to (when I'm not in the stupid hospital).
Like I said, PM me if you ever want to discuss it further. I've kind of made it a personal mission to read every article ever written about POTS, neurogenic orthostatic hypotension and autonomic failure, so I've learned a lot...