Hi,
With a normal T4 and T3 and a low TSH, you should have been diagnosed with subclinical hyperthyroidism. Since this disorder is usually Not treated, your doctor may have not mentioned it but, as recommended, regularly re-tested your levels. A low TSH on its own doesn't cause any damage. TSH is a pituitary hormone that helps regulate thyroid hormone levels.
When thyroid hormone levels (T4 and T3) begin to rise the pituitary secretes less TSH to try to keep them from rising too high. TSH will be as low as <.01 before thyroid levels rise abnormally high.
If you do have Graves' disease now, medications like methimazole can be used to lower thyroid hormone levels and help your immune system heal, causing remission. Graves' is a self-limiting disorder that runs its own course (often waxing and waning, and worsening in times of stress) and then resolving. best, elaine