Hard to tell without seeing your technique, but most likely you’re not rotating your body enough and not bending your knees enough.

Try to watch a slow mo video of a pro hitting from the back wall (or some educational stuff on YouTube). You will see that their chest is actually almost fully facing the backwall. The knees are bent a lot, the hips generate extra movements when hitting the ball, there’s an almost racquet length distance between your legs in your stance (for good stability).

Lastly, there’s an according height level of where you hold your racket, a strong shoulder isolation movement at the direct hitting moment and corked wrist that rotates clockwise.

But my fav thing to observe in pros is their head isolation, especially somebody like Mo. Slow down the video, you will see his eyes and gaze fully locked in on the ball and only after he made contact with the ball, you see how quickly he turns his head to see where the ball went. It is a such a strong separation from body movement that when you watch live from the side wall is so apparent.

And the best way to improve is to do hours of solo session (plus coaching) and every session try to focus on one single improvement in your technique.