Hi cek–First, I think you have the terms reversed. Hyperthyroid means too much, and hypothyroid too little. If your heart rate is still high and you’re still on beta blockers, it doesn’t sound like your thyroid was eliminated (only your doctor can answer that question though). Some people have to have a second, and some even a third RAI treatment to get the desired effect. Others just take longer for the thyroid to die out. The RAI doesn’t always destroy the entire thyroid. . .some are left with just enough to supply the right amount of hormone, and avoid thyroid replacement for many years.
Actually, there are cases of people who have gone hypothyroid after RAI, started on replacement medications, and subsequently gone hyper again, as the remaining parts of the thyroid recovered enough to “act up” again.
My understanding is that most people who have RAI go hypothyroid within 2-6 months, but just about anything is possible. I don’t think it’s realistic to expect to be “back to normal” in a couple of months. My endo told me it would be six months to a year before that happens. It’s been almost six months, and I’m not there yet (still trying to adjust replacement dose).