You're... failing to load your right side during your backswing. Instead, you're leaning your upper body toward the target and stranding most of your weight on your left foot.
By Brady Riggs
with David DeNunzio
Watch New York Yankee reliever Mariano Rivera (or any other Major League pitcher) and note the way he transfers all of his weight to his back foot during his windup. There isn't a single ounce remaining on his left side (in fact, his left foot is off the ground). When he makes his move toward the plate, he transfers all of his weight to his forward foot, giving him maximum velocity.