Post by Zhenbuyaoshi
Exchange one of your +12sp/+10haste gems in your belt for a +20 hit gem, and you'll be hit capped. You don't want to miss anymore of your spells than you MIGHT have already missed! The hit cap for you with your 3 points in Supression is 368, so get that gem switched out, and you'll be sitting just right at 372.
Next, get an Addon called QUARTZ or QUARTS, it will show you when you can actually hit the button to cast your next spell even when you don't think you can. This will up your dps by at least a few hundred, no joke. http://www.wowarmory.com/character-sheet.xml?r=Elune&cn=Zhenbuyaoshi
My warlock isn't nearly as geared/statted out as yours is and does about the same dps as you describe, and yes it is frustrating. We lost a significant amount with the last big nerf at the bottom of our destro tree, boo on that one. But, if you are keeping up a fairly error free casting sequence of:
CURSE(whatever you choose doom/elemnts), Life Tap, Immolate, Chaos Bolt, ConFlag, Incinerate until Conflag, Reapply Immolate, and then repeat casting chaos bolt as often as the cooldown comes up, same with conflag, incinerate is the filler and will be cast the most, and keeping Immolate up at all time, as well as Life Tap, then you should be doing Max dps in destro spec.
WATCH your QUARTZ meter for when you can click your next most powerful spell to be cast in your sequence! When the meter moves into the red zone, you are ready to click your next spell, and you'll be surprised at how much extra time that is! If you don't watch this meter and keep up with the red zone for casting, you will lose spells over time, and as you lose spells over time you will lose thousands of damage over time.
Lastly, Do your best to not miss those Conflags that will be VERY close to the end of SOME of your immolates as those speed boosts are worth tremendous dps bumps, and if try to get in that last immolate you might miss the conflag, and that sucks :-/ Hope some of that was helpful!