Made this yesterday.

>>7617968
You failed to make it feel three-dimensional. In the reference picture, notice how the forward knee and elbow are subtly bigger than their background counterparts, which creates an impression that they are closer to the camera. Also notice how the shading and clothing folds in the stomach work to give an impression that she's leaning forward, whereas your subject, without depth, feels like it's just tilted to the side.
Also, you made the limbs too thin, especially the legs.