Thanks Wrensong. I haven't been trying to lose weight, I'm a normal BMI and happy there. But in the past, if I ate any more, I gained weight. So I was stuck eating about 1200 calories a day and didn't know how to get out of it.
I found this great podcast (which others might want to check out) called Metabolism and Menopause. It has details on how to do a reverse diet. With a reverse diet, you figure out your current maintenance amount of calories (what you can eat without gaining or losing weight) and then you eat that consistently every day. Then you increase by 100 calories every 2 weeks. It is such a small increase that your body doesn't 'notice' that you increased and you don't gain weight. (You might gain a small amount over the entire reverse diet but not much.)
So I've been doing that and I'm now up to 1800-1900 calories. I haven't gained any weight, in fact I lost 3lbs when I first started because I began a bit too low - my metabolism sped up as soon as I started to eat regularly and I didn't increase until I was due to... I only weigh myself once a week because it's just one metric.
I'm also doing strength workouts about 3-4x a week using the Caroline Girvan app (highly recommend) and I'm eating about 120-150g of protein a day.
When I fold my arms, my biceps surprise me. My glutes are now a little shelf.... So... even if I do gain weight, it is highly likely muscle now.
So the plan really is to increase like this up to 2200 calories - which is where I should be - and then to come off thyroid meds. Exactly how to do that (fast, slowly, T3 first and then T4 or both together) and whether I should temporarily cut calories whilst I do, I'm still figuring out...
With the thyroid meds, I do think that taking a very low amount of T3 only (15mcg) worked well for me and boosted my own T3 without suppressing my TSH. But my stupid doctor (who is supposed to be an online thyroid specialist - this is not Dr Momi, it was who I saw before him) freaked out because that low amount of T3 sent my T4 below range. So then she insisted I also take 50mcg T4 and convinced me that this was highly likely the cause of my insomnia and awful night time symptoms (that were destroying my life). So of course I took it. And that (along with the 15mcg T3) was enough to suppress my TSH and make me need a full replacement dose.
I just hope my own thyroid comes back online fine and that whatever this miracle is which is letting me eat so much every day continues, even when I am off thyroid meds.