I know the hrt can affect levels if you are taking thyroid hormone. So I think it would be possible that if your thyroid was already struggling to keep up with demand, the hrt made it even harder. This is only a guess and me trying to reason. While you're waiting out the three months, you can make sure you're eating well and avoid raw cruciferous veggies (broccoli, kale, cabbage, etc) as those can put a strain on thyroid function too. It could be that it's just declining in function and you'll need a little thyroid hormone.