You need a solid stance when you're firing a bow so a step back makes sense, but you would be planting your front foot solidly and stepping your back foot back, not moving your front foot like you do currently. The main issue I see with this is it's very understated. You're pulling the bowstring back perhaps a hand span when in reality archers will pull the string back the entire length of the arrow. Arrows are pretty long so that means a very stretched out bow. The force from a bow, contrary to what you might imagine, comes from the bending of the bow itself and not the string. What this means is you need to pull the hand back a long way, maybe even to the shoulder, keep the string the same length and pull the ends of the bow in towards it, it's a bit of a tricky piece of geometry so have a go sketching it out and making sure everything always stays the same size and it's just the bow bending that allows the hand to move back. I can see you've made the bow bend outwards after the shot is fired which is great! That's called an overshoot in animation terminology and I think it's essential to a good bow animation, but you're adding pixels to the bow rather than bending the pixels that already exist.
I suggest you retry this animation but don't move the body at all at first, just focus on making the best hand and bow animation you can and you can try doing the step after you've got that sorted. Also, I suggest you expand your canvas, I can tell it's limiting you.
Good luck
