The most important element of your 'pre-shot routine' is aiming/alignment. Alignment should be found BEFORE you get down on the shot and into your stance.
So, if you are swaying from side to side after you are already down on the shot, then you have not properly aligned at all and your ability to aim is hindered as you are not even confident that you are actually in line with the shot you want to make.
Do youreself a favor and begin to aim/align while still standing up, then bring your alignment into your stance and finish with checking both your aim/alignment 'without' swaying. If you feel the necessity to sway, then you are not confident you are aligned correctly and must stand back up and re-do the entire pre-shot routine.
You must have not only self-awareness, but ultimately the confidence in your awareness and execution of your pre-shot routine perfectly before you will stop swaying and start shooting the lights out.
(Also, make sure your eyes are on the 'object ball' when you are shooting the ball.)
KJ Williams
kj@cuesportcollege.com
www.cuesportcollege.com