I’m fat.... and I don’t know what to do 😭

I have been relatively “thin” most of my life. I have gained 15 to 20 lbs in the past few years after my last baby. My hips, butt and legs (all the way down to my ankles) are full of fat and cellulite. I hate it so much! I’m not sure what to do. I know diet and exercise. But, even when I was thinner and was working out I still had heavy legs. They were “better” but still embarrassingly heavy. Does anybody else struggle with this problem? Help!! 😭