How to make form fitting garments without lace-up back?

I've made this top out of 100% cotton yarn quite a while back and every time I wear it, it stretches out in like an hour to a shape that's not at all form fitting.

The design is self-made but the construction is similar to the 'Lyra crop-top' by Hey Carrie.

I've only ever made lace up bralettes etc. or loose fitting stuff. Looking back at this top, I probably would've used a smaller hook for the ribbing, but it's already a hassle to get into this top. Currently I'm thinking about using elastic to cinch it in on the bottom.

What are your methods or go-to tips?