>>1016718
>>1016714
The reason you can't subdivide your mesh without ruining the shape is because of what subdivision is does mathematically to determine where to place its subdivisions, and there's not enough geometry around the tighter areas like the inner thigh. You'll have to retopologize what you have for good deformations. However I'll take a different approach from the other anons and suggest studying from models that you like. Smutbase has thousands of models with different ass shapes. Find the 'tocks you like and try to build it from scratch. A lot of 3d anatomy topology tutorials (that are free) aren't very good but if you're getting a headache just pay for a well reviewed tutorial series. Those are pretty fool-proof in that they filter all the fools and depending on the series you can get no nonsense workflows that give great results.