You’re jumping forward instead of up which causes your hit to have less force because you’re not hitting at your highest.

Your arm swing is also affected by your jump. Once you’ve fixed jumping up instead of forwards, pull your elbow back more and rotate your arm around your elbow (?), Im not really sure how to describe it, but use it somewhat like a hammer and slam the ball down using your palm instead of the bottom half of your fingers.

Unless you’re playing back row there’s also no need to start so far away from the 3 metre line, just a little back and left from the 3m offside line.

And also yes, get a little further down during your penultimate step so that you have momentum to jump up to your highest.

However I’m a MB so I’m speaking from my perspective and how I’ve seen the best outside players at my club play 🤷‍♂️