"No follow-up given"

I visited the Diabetes and Endocrinology Department in May this year for an underactive thyroid and was told I would be followed up in 6 months' time. I have had no letter confirming this and I can't understand why, since I am still not feeling well and if anything my thyroid medication is making me feel worse despite my GPs saying my TSH is "normal" but my thyroid hormone levels are low.