Hello, Feary! I'm not sure from your post what you see as the "huge mistake." Do you believe that accepting meds in the first place, leading you your weight gain, was the mistake, or was the mistake weaning off the meds?
Regardless, this is a real dilemma. Have you made it clear to your doctor just how distressing it is to need meds that tend to put weight on you? Does he or she care?
Managing medical trade-offs is no fun...
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My dog

mastered the "fetch" command. He would communicate he wanted something, and I would fetch it.