Your spec is a bit off... Your missing the threat talents.
Drop Puncture Improved Disc, and Bloodrage
Put a point in Damage Shield and max out 1 handed spec.
Drop Iron Will and Anger Management.
Pick up Heroic Strike, Impale and Deep Wounds.
Cnage Booming Voice to Cruelty.
Work from there, keep Deep Wounds for now until you get a better handle on threat. Improved Disc or for Ulduar.
Change your glyphs, Shield Slam, Cleave, and choose your third. Heroic Strike, Revenge, and Shockwave are all favorites, but I've found most trash pulls happen every 20 seconds, perfect for an unglyphed SW.
Charge in, Thunder Clap, Line up the mobs, Shockwave, then rotation Shield Slam > Revenge > Dev. You'll find when SW wears off TC is back up, I usually interrupt my rotation to toss out another TC as soon as it's up on trash. While doing your rotation tab through the targets after every GCD or two. With Cleave hitting 3 mobs you can keep aggro on them all till they are dead.
Put a shield spike on your shield, enchant your gloves with Armsmen, get rid of the parry gem in your helm, use expertise or expertise/stamina for red sockets. Get a socket for your belt, gem more expertise. Get an expertise enchant on your wrists and icewalker on your boots.
See where your at once you get that done.