My wife has hypothyrodism which runs in her family. The problem we had was that her doctor did the requisite tests and found she was high but within the 'normal' TSH levels. My wife was at 4.8 when first tested. She was put on low doses of medication but didn't see any real improvement.
We did a lot of our own research on the internet and found that the traditional range of normal TSH levels of 0.5 to 4.5 or 5.0 are out of date yet many labs and physicians still use them. Recent research suggests that the new upper level should be set at 3.0 and some research suggest going as low as 2.0.
My wife found a new physician and armed with some of this research, had additional tests done including T4 as well as T3 levels. Based on the results and her symptoms the doctor agreed and changed her medications and dosages. It has been a couple of months but she is starting to see some results, especially in her moods and energy levels.
About.com has a good article on this issue you can read here:
Do some research and talk with your doctor about the most recent studies. Some doctor's and labs are slow to change from well-established standards. Don't quite pushing until you are satisfied. Good luck!