I'm not sure If I'm the type of unholy dk you are looking for, but I am 2/8 herioc progression, which is the same as you. and also your ilvl seems slightly higher than mine, so dps should be similar.
Fights you would probably want to use unholy over frost on would be morchok, zon'ozz (not sure about heroic, considering the adds), ultra, and maybe deathwing.
the few tips i could give (fight specific things) would be:
1) (not so fight specific) ams is a huge dps boost if used properly. sometimes it requires you to stand in fire just to get a dps gain. an example being second phase blackhorn, whereyou should stand in gariona's fire when ams is up for a huge rp gain. just make sure if you do this you pay attention to the durration of your ams and don't end up killing yourself.
2) for ultraxion, make sure that you don't use ams when he is casting hour of twighlite (unless it is heroic and you are taking the hit) and make sure that you and your group are close enough to him so that the gurth tentacle can hit him.
3) (this works on lfr, have yet to try it on normal/heroic) durring black blood for morchok, pop ams. extra rp + extra uptime on boss = win
4) for madness of deathwing, first, on regenerating bloods just use DnD then spam blood boil and spellweave will proc like crazy. you can get at least 3 million damage out of spellweave diong this. second, the key to good dps on this fight is 100% uptime when you get a the 100% damage boost on the wing/arm ( by uptime, I mean you should not run out of resources at any point).
5) (not sure if you will get this far, conidering only 1 guild is on H spine and this is your alt) but on H spine, diseases don't have an AoE damage cap. pestilance on bloods with 7k blood plague and 3k frost fever ticks per target will do insane damage. this works better on 25 than it does on 10.
an in general tip that you should know about the rotation is that 1 DnD > 1 scourge strike. ~ 10k more damage if the entirety of the DnD is allowed to tick. continue to use scourge strike when the boss is moving/about to move.
macro at least your main abilities, all of them if you like, with claw. Our pets are not very smart when it comes to using their resources.
#showtooltip Scourge Strike
/cast Scourge Strike
an example of the macro
also, get rid of glyph of icy touch, replace it with glyph of death coil.
lastly, I have been looking at stat weights for dk's and have been finding mixed results, some have mastery > crit > exp, another had crit > mastery > exp, last one had crit > exp > mastery. I am going to look into this, and respond later when i discover what is most optimal. but looking at the #1 parse for Ultraxion, he had onlt been dodged 1 time durring the entire fight, which has made me think if option 3 for secondary stat weights is most optimal, or said dk got extremely lucky with rng.
really, the general idea that turns you from a good dk to a great dk is proper use of ams and knowing the fights, which you basicly know already. you should have no problem doing 30-35k dps in your gear.