There's something very wrong with your taunt missing 75% of the time. Unglyphed (and without virulence) Dark Command has a 17% chance to miss. That's why the glyph gives you 8% to bring it down to match your melee attacks at 9%. If you were missing 75%, you were either affected by DR, or doing something strange.
About your rotation, don't bother with DnD for single target tanking, it's not worth the 3 runes, and you need to use Blood Strike to transform your blood runes into death runes for an extra obliterate on your next round. FS only if you have more than 50 RP. Don't forget to use Deatchill on your OB and BT for an extra BS. So your rotation would look like this: IT-PS-(death chill)OB-BS-BS-(blood tap)BS--(FS Dumps)--OB-OB-OB.
Make sure you have a way of spotting your KM and Rime procs (I use SBF, but you can also use ghostulse to get flashy icons, or MSBT to get it as a text announcement). Use FS when KM procs and HB when Rime procs.
Also, macro RS to all your abilities, so you don't have to worry about it. For instance, your Obliterate macro would look like this:
Do the same for all your primary tanking abilities (IT, PS, BS, BB, HB, OB, etc), and you won't have to worry about RS anymore.
/cast !Rune Strike
Your spec looks fine, but the UA glyph is a PvP glyph. Try the glph of RS or FS instead.
I also noticed you have the glyph of HB, with the glyph of HB some people like to skip PS or run with a rotation like this: (Deathchill)HB-OB-BS-BS-(blood tap)PSorBS--FS Dump--OB,OB,OB. The advantage of this rotation is that you can HB as you run in, and it helps building a lot of threat from the start. The disadvantage is that you can't really be refreshing PS smoothly unless you use blood tap, so you'll probably end up sacrificing one disease.