If there is an integrative doctor in your area, perhaps see them and ask if they can provide you with access to crushed pig's thyroid as a medical alternative to thyroxine.
Thyroxine is dose in 25 mcg increments which doesn't always account for body size well and most people on thyroxine are overdosing without realising.
The risks of overdose of thyroxine is yin deficiency.
Of course this can be balanced with herbs but thyroxine is a very sensitive drug when taken orally so many oral herbal administrations can interfere with its effectiveness.
They are best prescribed by a physical practitioner with whom you can touch base often.
Integrative doctors who work with Chinese Medicine specialists would be the best group of people to see regarding your ongoing management of this condition.