Your labs and body temps sure sound like a classic presentation of "Low T3 syndrome." It's too bad your doctor didn't take the time to explain this to you, but luckily, Chris Kresser has a pretty good, easy to understand article about this:
I cannot stress enough how important it is for you to take your thyroid seriously--if you fail to address this, you health WILL deteriorate slowly but surely, and you will be miserable. And this need not happen. Causes and the best treatment may take a little time to figure out, but treatment is not particularly burdensome or difficult, nor even expensive. Depending on the cause of your troubles, you may be dealing with your thyroid for the rest of your life, but as chronic conditions go, thyroid isn't too bad--provided it's well managed.
After reading the above article, I suggest you browse ALL of Kresser's thyroid articles for a deeper understanding, and some perspectives that will likely be somewhat different than you doctor's. Start here:
As a lifelong thyroid disease patient--first hyperthyroid, then (and now) hypothyroid, with a mother, two grandmothers, and a sister with the condition, learning about thyroid disease has been something of a lifelong persuit for me. So I've done considerable research. I have to say that I have been pretty impressed with Kresser's work and perspective on this topic. But just be aware that he is not an MD. On the other hand, I have been failed by so many MDs over the years that I hardly consider that a credential that automatically confers legitimacy on a healthcare professional. Use your best judgement, but be very critical and follow up everything with more of your own research. And that research should obviously NOT be limited to advice you get on Palehacks.