Checking your armory, I say go Unholy.
From what I've seen when I was raiding with under-geared and well-geared DK's alike, I noticed that Unholy doesn't scale as well with gear when compared to Frost/Blood.
Thus, as your gear is average (for the moment), go Unholy and Scourge Strike things to death. Plus, as you have a 2pc t7 bonus that is completely going to waste by using Blood, it is even more reason to go Unholy to utilize the +5% crit to SS.
As for your gear, fix your gems, replace the Boar Trinket with a Mirror of Truth ASAP, change your Meta as there's no reason to have -10% to Stun durations and get yourself a Sigil of Awareness.
Once you get yourself Uldar 25man + 2p t8/8.5 or better, consider spec'ing Blood. Until then, go Unholy. Oh and with the change to Unholy Blight, you MIGHT want to try the Sudden Doom/Morbity+Unholy Blight spec once 3.2 hits:
Talent Calculator - World of Warcraft
That spec doesn't feel very solid so if someone could correct it, would be much appreciated.