HI Dianne, I think the testing they have to find out what is REALLY going on is insufficient. And mercury can bugger up the actions of these hormones, but still show there is "sufficient" available....this is why people like us can wind up miserable and without a proper diagnosis. I think you know yourself better than these limited tests and your temperatures are evident your thyroid is low functioning. That plus your symptoms as well, which is kind of classic.

Before you start on any replacement hormone, even if it's natural, you might want to read this article and see what you think of this first!
http://www.alkalizeforhealth.net/Liodine.htm

This maybe helpful to you.