Hi, I Am A 28 Year Old Girl With Graves

Hi, I am a 28 year old girl with Graves disease and also Type 1 diabetic. I was diagnosed with overactive thyroid a year ago and was on 20mg of carbimazole a day. I am currently now taking 10mg a day but i have gained over 12kg and i am struggling so much to bring it down. I exercise regularly 3-4 times a week at the gym and eat as best as i can. This is ruining my confidence to the point where i just want to stop taking my medication. Is there anything you can advise?