I would really encourage you to get your thyroid levels tested. There's a TON of good information in the link that Pirouette posted, plus you can order your own testing if need be:
www.stopthethyroidmadness.com/recommended-labwork/ Usually the only test many doctors will do will be the TSH and sometimes they will order T4 testing, but we need more thyroid hormones tested than that to have a REAL picture of what's going on. Even then it may be hard to understand. My levels have always been near the center of "normal", but I've had very obvious low thyroid symptoms - meaning that my body isn't utilizing the hormones that it has available very well, so I need to be on both T3 & T4 supplementation in order to reduce my symptoms.
Routine testing will be needed in order to monitor your thyroid status and find a good dose for you, so it's best if you can find a doctor that will work with you on this.