Take a stick, knife or whatever that's nearby, and hit the wall with it. See you move more than your arm? See your arm starts bent, and stretches out towards the end, see your torso rotates to increase power or range, see your stance is much, much more stable than what is shown in your sprite now. Shortly said: study movement before you draw it, never guess in CG, it won't look right.

Other than that, play the idle frame -> then the attack frames 1,2,3,2,2 (yes repeat, pull back is slower than attack, as you attack with full force),and then the idle frame again. Having 3 frames, doesn't mean displaying just these 3 frames. Code is cheaper than pixels, so if you have 4 frames because of a memory limitation, solve it with code. If you have 3 frames for no reason, use more and increase image speed.