I used to have the same problem. I have thicker/muscular type legs. My waist used to be small and to get jeans to fit in the legs, the waist gapped badly. After having a kid, my waist thickened up so they are fitting better but it's still a problem with some styles/brands.

Jeans are uncomfortable for me. The material is painful. I adore jeggins. They allow me to wear jeans and feel like comfy stretch pants.

Levis fit me pretty good as far as brands go. But I hear ya, it's a struggle. They make clothes for average proportioned people. Women vary in size/body shape that it's no wonder we have this issue.

Maybe find a good tailor? It can be reasonably priced and you will end up with a custom fit. Better to buy larger and have them taken in. In a perfect world, we wouldn't need to worry about this, but it is a first world problem so we must adapt.

Good luck in the jeans department. Genes makes jeans hard.