Most patients seem be fine when their hypothyroidism is treated just with T4. Some patients are not despite normal blood tests, these patients continue to complain of symptoms. It would be worthwhile thinking about a T4/T3 combination in these patients.
Combination therapy should not be an automatic choice without further evaluation just because the T4 therapy has proven ineffective. It is very important to think in a wider sense also. For example does the patient have another autoimmune disorder giving the symptoms, this could be pernicious anaemia or Addisons disease or Lupus. Does the patient have a contraindication to changing standard treatment i.e is the patient pregnant or intending to be?
The best advice at this stage is to keep an open mind. If you think T4/T3 would be a better option for you then discuss your concerns with your endocrinologist.