If, as mentioned, you're going to the doctor soon and he'll be taking care of testing you may not need to bother with the following links, but if I were concerned about my thyroid functioning I'd read this:
"While this test [TSH] is commonly used, and recent improvements have made it more sensitive, there is a good chance that the standard reference ranges used by many laboratories are so wide that many people with subclinical hypothyroidism are not correctly diagnosed. This means that potentially tens of thousands of people suffering from depression, heart disease, or weight gain may be unaware that their conditions are actually due to low thyroid hormone."
Thyroid Regulation: Online References For Health Concerns
and have these blood tests done:
Thyroid Panel (TSH, T4, Free T4, Free T3) Blood Test