You are very much crushable in that gear, so here's some of my advice for gear. I don't know if these changes will get the uncrushable since I'm not a numbercruncher but they will help.
I second the Bracers of the Green Fortress, but if you can't get those then the Sha'tari Wrought Greaves (http://www.thottbot.com/i28167) are from a quest chain and are pretty good too.
For your neckpiece, buy the Strength of the Untamed from Cenarion Expedition:
http://www.thottbot.com/i29173 , it will up your dodge considerably, although you'll take a hit in stam.
Your cloak isn't very helpful towards your defenses, I would recommend either the cloak from the first boss of Steamvault - Devilshark Cape (http://www.thottbot.com/i27804) or from Black Morass - Burnoose of Shifting Ages (http://www.thottbot.com/i27988)...although the Devilshark Cape is seemingly a rare drop.
Your sword could be replaced by the Continuum Blade for 15 more stamina from the Keepers of Time.
Your current spell crit ring is worthless for you though, I'd say replace it with that Ring of the Silver Hand from before because of the defense on it.
You could also change the Helm and Gloves of the Righteous with Felsteel crafted items, they have more to offer in defense and stamina with gems if I remember correctly.
You could also look into replacing your +8 defense gems with +4 Defense/+6 stamina to make sure you stay above 490, or go with agility or dodge gems if your defense is above 490 still. There are also enchants to get, such as +150 health to chest, +12 stamina to boots, and either dodge or +12 agility to whatever cloak you go into Kara with.
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How'd you manage to get the second Karazhan ring already? lol