"Normal values are from 0.4 to 4.0 mIU/L for those with no symptoms of an under- or over-active thyroid.
If you are being treated for a thyroid disorder, your TSH should be between 0.3 and 3.0 mIU/L. This means that you are being treated appropriately.
Some people with a TSH value over 2.5 mIU/L who have no signs (that is, no other abnormal thyroid function tests) or symptoms suggestive of an under-active thyroid may develop hypothyroidism sometime in the future. Anyone with a TSH above 2.5 mIU/L, therefore, should be followed very closely by a doctor.
Normal value ranges may vary slightly among different laboratories."
"Greater-than-normal levels may indicate:
Congenital hypothyroidism (cretinism)
Primary hypothyroidism
TSH-dependent hyperthyroidism
Thyroid hormone resistance"
My assumption is that due to the supplements that you are taking, your body is producing significantly less of this particular hormone on its own. If you are now off the supplements you should probably get anoter test and make sure your TSH levels return to normal.