Hi, I Am On Thyronorm As My Thyroid Test Result

Hi, I am on Thyronorm as my thyroid test result was 6.15, my dr told me to take it for 2 weeks and have a test done again and 2 weeks ago it was 4.15 so it has come down but dr has told me to keep taking the thyronorm for 4 weeks on alternative days which I am doing. I am normally a regular gym person and eat healthy but being on this medicine has made me gain weight, I am walking every morning, I eat healthy avoiding all sugars, bread etc and eating mainly fruit, veg and protein. Dr said not to do high intensity exercise yet to wait, is this right should I not go to the gym and wait until I have my next test done in a couple of weeks? My main area is stomach and upper body I am holding weight, I have always been very small and lean so it's uncomfortable for me.

Please can you advice me.

Thanks