A wonderful site for hypothyroid folks is http://www.stopthethyroidmadness.com.
The owner of that site has a yahoo support site: NaturalThyroidHormones. If you post your test results there, mods can help you interpret them for you. But, from what Janie recommends, you want the Free T3 and Free T4 tested because it gives you a better indication of what is actually happening in the thyroid. She also recommends that you get your ferritin tested. If levels are below 70, then the meds can't get to the thyroid. I don't know anything about the accuracy of urine thyroid tests. STTM recommends blood tests.
It's the general experience of most on the thyroid board at yahoo and Janie's experience talking to all those who helped her get the research for her book that over the counter gladulars are really not potent enough for hypo folks. They usually end up on rx meds like armour, naturethroid or westhroid. If you are taking these glandulars, be sure that you also include selenium and tyrosine to help the thyroid. Also, get your vitamin d levles tested. I've recently read that inadequate levels of vitamin d prevent the body being able to utilize the amino acid tyrosine to convert to the necessary thyroid and adrenal hormones. You should also be supplementing with Iodine using a supplement like lugols, iodoral or even magnascent Iodine and trappers super saturated potassium iodide. Go to the curezone Iodine boards for info on trappers SSKI .