Congrats on your Shield 45 selection, mine has simply been awesome!
Your best deals are likely to be in 45 cap 230gr rounds. Pretty much the standard round for 45acp.

Take a close look at your front sight, is it dead centered in the groove or is it a little off to the left when looking at it from behind the gun?? This may tell you why you are shooting to the left.

Concentrate on the front sight being dead flush in the rear sight recess, the short sighting radius is pretty demanding on technique. How high at what distance?

As far as ammo, you may find better deals on the 100pks of ammo, Remington, Winchester, Federal, American Eagle and Blazer ammo are common name brands.

Just remember the chart being offered on Pistol Correction is for a 'single' right handed shooter, not a two handed shooter or a 'single' left handed shooter.

Karl