This is good stuff for your very first animation. Keep it up. I like the new work you added but I think the back leg shouldn't move as much or shouldn't move the way it's moving now. The edit rologfos made are good and I think you should draw the characters back leg closer to that pose/angle then animate it. It's the correct way you'd position your back leg if you where to take a shot like this.
Maybe you can pause the character for a micro second right when he's about to take the shot so it looks like he's concentrating or aiming. I think that will give your animation some flair. Also, I think the lower body seems to be bouncy or jittery. That's maybe why it looks off in my opinion.
Maybe you can redraw the animation with your character just moving side to side during his gun blast and see how that looks. Look at every ones pixel art and pixel art edits in this thread and notice how the lower body of the character isn't shifting up and down during the blast. Try and replicate that.
