I would listen to the doctor that wants you off it, if I were you. Your FT3 is under-range! Not surprising you feel bad. You can always go back on it if necessary.
One thing you could do is stay on the tapazole while adding in levothyroxine to bring your thyroid levels up. Your antibodies are still above the reference range and tapazole does help lower them, which is why you don't want to stop it just yet. This page talks more about that protocol: tiredthyroid.com/graves.html
How long have you been on the Tapazole, how long have you been within range, and has Graves’ been confirmed with antibody tests or by some other means ?
So you should be ok to stop, but an alternative would be to try halving the dose (or taking it every other day), and see if that makes the difference. If one of your docs is a specialist endo, would be worth asking how long you need to stick with the medication.
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