Synthroid is a forever drug, as with all supplementation if the body is getting lazy or damaged in the factory of chemical production then you will not be producing the necessary levels of hormones to regulate your body life processes.
Do you have access to a ND in your town? If you can not afford it tell them so, and discuss the transition with them. Some are known to take on cases, others are willing to discuss your idea and let you know the upside and downside and why.