I asked my endo once about OTC for Thyroid, he said "there are not any, those that claim will help thyroid function are just out to make a buck".
Although there are supplements that may help you feel somewhat better, perhaps temporarily, hormone replacement is the only thing that is going to make you feel well. There are no OTC supplements that contain measurable thyroid hormones.
What about finding a doctor who understands thyroid, the limitations of the ranges and will pay attention to your symptoms? If you interview prospective doctors over the phone, you can really increase your odds of getting a good one...