Your spec is wrong, your gemming is all over the place, you have a tank sword in your offhand, a dagger in your MH as combat.... I could keep going.
Your best bet is to read a guide. I suggest the Pocket Guide for Rogues 3.3 over at ElitistJerks.com and then make changes based on that. Once you have made some changes, evaluate the changes, and then come back here for further help. But you need a base first.
I'm going to agree with the above poster , but if the site seems overwhelming 1 thing you might want to consider is (as combat) you dont want to use a dagger on your main hand , ever and drop the tanking weapon, it isnt helping you .
Here is a link for a normal combat spec http://www.wowhead.com/talent#fhg00t...0cxqru0xRt:Nhk , your looking for swords or axes for your weapons , keep Slice and Dice up , main finisher is eviscerate.
-I don't think you need 6 Stam gems.
-Replace the Tanking Sword of course.
-There are 75 stam/ 25 agi you can make with your LW skills.
-Don't Enchant into Stamina. (talking about your gloves, boots)
-You don't always have to get the socket bonus, you can stack AP or AGI etc, Could make you pull more DPS.
You're going to want a sword/axe in your main hand, and a fast weapon on off, fast/slow (instant/deadly on poisons). Gems are off, I gemmed ArP once I hit about a 4500 gs, you shouldnt be using any stamina gems, only red gems in red slots, orange in yellow (stark ame), and one nightmare tear in a blue socket if the socket bonus is worth it. But I mainly gemmed ArP and my dps sustained is pretty good. Keep snd up and rupture and weave in eviscerate.
I have to admit, when I first looked at your armory my first instinct was that this was a troll attempt. Please tell me it's a trolling attempt? I guess at least there's no intellect or spirit gems in there which is a bonus. Looks like you been into ICC at least once or twice so you've either found a very patient guild/groups or your having a lend of us?