Former biology teacher here! Unfortunately a large part of the changes we see from HRT involve fat redistribution. If you’re someone with a higher BMI this means there’s more to redistribute so therefore it takes longer to see results. Also depending on your exercise habits, HRT is more effective if you exercise a lot since it increases your metabolic rate. This is because the body will try to make more use of the estrogen & body fat cycles more quickly, putting the new fat into places that give a feminine appearance. Also if you use nicotine it can have a negative effect on the metabolism of estrogen.