Welcome to HCM,
In your case Hypothyroidism
must be given special attention as requirement of Thyronorm
is increased that is why dose was increased and after delivery reduced, it is important to take adequate dose but take care it is not over dose and needs to be monitored by Free T3 Free T4 and TSH
Please do not reduce dose of Thyronorm yourself,and consult your treating Physician to examine and repeat thyroid function( Free T3 Free T4 and TSH) then dose can be adjusted.
Please take care of your diet and exercise , if there are no other health problems.