i think that the catastrophic thinking may be a bipolar trait, because my T and Pdoc both talk to me about that, be careful about going into catastrophic thinking. so now, i actually can sometimes notice when i'm going into it and kinda try to rethink the situation, because rationally i know i do not want a panic attack to come on. or maybe the intensity of the catastrophic thinking is a precursor to mania and depression - so if there's any way to talk yourself out of it - do it.
also - maybe you dont need to taper off the meds at such the rate, maybe they could let you take longer to taper off if that would help calm you.