Gaping in jeans

Does anyone else have the issue with Gaping in the back of their jeans? I’m pretty petite I’m 5’0, 108 pounds and a size 0. Everything single pair of jeans I’ve ever tried on does the gaping. Does anyone else know how to fix this? I don’t repeat have hips so I think that’s part of the issue 😂 I would possible try a smaller size but I’m pretty much at the lower end of sizes most stores don’t carry 00 and beside I have muscular thighs so my calves can’t don’t into those 😂