If you see a doctor about this and he can explain it to you or track down the problem, please let me know. I have the same thing. My labs are fine except I have to take iron for anemia, but even with normal numbers I'm freezing all the time. But people touch me and think I'm like an oven. My thyroid has never been a problem lab wise. No lumps found ever.
It might be an idea to make an appointment with your family doctor.
Losing 6 lbs without trying or not on purpose would be concerning to
me. You could talk about your low metabolism at this time too. Good luck. Eve