Messed up metabolism

Hey all, I just wanna start by saying I love my body. Except one thing. About a year ago, I was put on a different medication that made me gain 25lbs in less than 4 months. That on its own is crazy. I know that as you get older your BMI and stuff changes so I’m not expecting to lose it all again. But after trying multiple ways to lose some weight, I still haven’t lost anything. I’ve steadied our at a certain number but that’s it. Help???