What I would do is change your +hit gems in your shoulders to Veiled Noble Topaz(or Pyrestone). Change that +8 crit gem in your leggings to a +9 or +12 spell damage gem. Change the +spell hit/+stam gem in your belt to a Glowing Nightseye(or Shadowsong Amethyst).
Then like Theleb suggested switching to a Mal/Ruin spec, basicly take 1 point out of Shadow Embrace, Unstable Affliction, and Imp. Healthstone and put them into Intensity and Ruin. That will give you a bit of a damage/dps increase.
Also if you have a damage trinket to use instead of the pvp one, like the Icon of Silver Crescent from badges, that would help a lot. GL
