You can just recheck your TSH to know whether its under control or not. Also you can ask your endocrinologist
to do some hormone tests to know exact cause & then get treatment. You have not mentioned your age, so its difficult to predict any cause. If you are taking Glucophage
just for PCOS ( and not for diabetes
or impaired glucose tolerance
) you can stop it after consulting your doctor.
Wish you good health.