hey there!
in all honesty, i think you're looking in the wrong place to make improvements! your gear isn't that bad at all. there are a few small changes i would make:
- swap out gems for +12 Sta gems where you can (gun is an obvious first chice).
- if you're having trouble getting hold of a 'real' tanking weapon, augment the one you have as much as poss with the +20 Agi enchant (or Mongoose if you can afford it).
- Get Glyph of the Defender on yout head (if you can afford).
But - all that being said - i think you would benefit most from getting yourself into a guild who is starting out in Kara. The benefits you'll get here far outweigh a few gem-swaps:
- less of a 'blame culture' on runs.
- people looking to progress into the same content.
- hopefully some other tanks to bounce ideas off.
- dps you can tell to slow down and healers you can ask to speed up

- fun times with fun people!
if you're not getting invited on guild runs - why? maybe it's time to look for somewhere where you will get spots on progress runs into heroics / kara!
HTH and GL!
- DW