Does hypothyroidism make you gain weight even though you exercise and are on a proper diet?

Recently found that my TSH levels range from 6 to 9.3 and my gynec said that i'm hypothyroid and should be treated but the endocrinologist said he won't treat me for thyroid unless i'm planning to conceive and put me on spironolactone 50mg to regularise my period. i'm eating as healthy as i can (i'm a dietitian, so i know what i'm doing) and i exercise (yoga, walking, weight training, cycling, etc one or more of these) totally at least 45min to an hour everyday. Yet my weight has increased slightly and it feels like i'm struggling to maintain it. Do u think this could be due to the thyroid problem. I'm so confused and fed up, please help me out.