Is my DK buggy ?

Hey. After 3 days spend to trying find what is problem with my DK (Unholy DPS) i am relly lost and i need help probably... For some reason looks like my DK is buggy and couple of things is not working correct, i will explain what is going on...

LVL 80 or Boss (doesnt matter) - i am not able to get more like 3200dps on single target.

(Bone Shield + Horn of Winter)

Single Target Rotation - Icy Touch, Plague Strike, Blood Strike, Scourge Strike, Blood Strike, Death Coil, Death Coil
Multiple Target Rotation - Icy Touch, Plague Strike, Pestilence, Blood Strike, Scourge Strike, Death Coil, Death Coil

Gear (not best, actually i am lvl 80 2 weeks)

5063 GS

Head - [Thassarian's Helmet of Conquest]
Shoulder - [Thassarian's Shoulderplates of Conquest]
Chest - [Thassarian's Battleplate of Conquest]
Hands - [Thassarian's Gauntlets of Conquest]
Legs - [Thassarian's Legplates of Conquest]

Neck - [Painfully Sharp Choker]
Back - [Tapestry of the Frozen Throne]
Wrist - [Wrathful Gladiator's Bracers of Triumph]
Waist - [Relentless Gladiator's Girdle of Triumph]
Feet - [Grinning Skull Boots]
Ring 1 - [Ring of Rotting Sinew]
Ring 2 - [Ashen Band of Might]
Trinket 1 - [Mark of Supremacy]
Trinket 2 - [Needle-Encrusted Scorpion]

Weapon - [Tyrannical Beheader]

Relic - [Sigil of Virulence]

I solved the problem with more players but we didn't figure out what happened. Everyone confirmed that my rotations are fine, my gear is fine at the beginning but my dmg doesn't match. When it comes to talent, I use "first build" Unholy + Blood. I met players like me and their DPS was 5k + with the same rotations ... Please help, this situation is very depresive when everyone is saying to me like "you are noob, dont play DK or dont play WOW".. Thanks

"Unholy + Blood" - could be this, blood subspec is relevant maybe on Frostmourne if at all
Do you use good gargoyles, get the good snapshot and does it go full duration?
Is your pet attacking?
Even 232ilvl stuff will have more stats than PvP pieces.(You are comparable to 4.8 gs or something along those lines)

Rotation is not this robotic "Icy Touch, Plague Strike, Blood Strike", that's just an opener. Btw how can you do 2xDC if you summon gargoyle for that RP??

Just play, look for info(because from info you provided even Jedi wouldn't be able to mindread whats wrong). Experience doesn't peak in 2 weeks.

P.S
Make sure you use top Rank spells, check all the macros and action bars.