Muscle definition doesn't have to mean, defining anatomy in the sense you may be thinking but in the transition between major forms in regards to silhouette. As posted by Snader, you haven't given any definition between upper torso, stomach, to hips, you just have this subtle S curve instead of really defining and pushing…
The proportions seem good and the height to head ratio is working. The main thing I'd say you have to work on are the muscle forms. She has no definition in her body, it looks like she could barely lift a donut lol. Like everyone else said, just use the reference a bit more and really try to push that silhoette. It's…