Iwrote this in another post but it works well here to.
Ok first I would like to say testing you DPS on a test dummy will NEVER give you a proper read, so spells and effect will not work on the dummy. This means we will alway see the wrong numbers. The only true way to test your DPS is in a 10 or 25 man raid on a boss with proper buffs.
That being said you I would use the reaping-less spec for your single traget. I use this spec on Snny.
You are using the proper rotation for the reaping-less spec and I would still use it. I use
PS, IT, BS, SS, BS, Gargoyle, DC, (DC), SS, BS, SS, BS, DC (burn), HoW
You will see I have the Gargoyle in this rotation. I use it every chance I get and do not wait for buffs. This is because the DK dps rotation is so tight you just may not have the time to wait for the right buffs to stack. Also popping it at the start and at the end of a fight is for the most part better then popping it one time buffed.
Now you will not max out your DPS if you do not use the proper Professions or Macros. I would if you can try and level up Jewcrafting or Engineering to replace your mining. Here are some macros I like to use:
The following are only for people with Engineering:
Army of the Dead
This will pop AotD with both the haste buff of Hyperspeed Accelerators and Potion of speed. Unbuffed this puts my haste rating at 888. I put /use 10 to proc the Hyperspeed Accelerators. Make sure you have your AotD before the fight because you can only use Potion of Speed on time in combat. If you use the Potion of Speed before combat you will be able to use it again with your Gargoyle.
#showtooltip Army of the Dead
/use Potion of Speed
/cast Army of the Dead
This will proc the Hyperspeed Accelerators when ever you use Death Coil. Remember that Hyperspeed Accelerators has a one min CD but it is off the GCD. I macro this to Death Coil because it is the best spell to effect your rune CD the least so that your rotation does not get messed up.
#showtooltip Death Coil
/cast Death Coil
This will proc Global Thermal Sapper Charge at the same time as Blood Boil. You will need to make sure you are not low in health when doing this as you will take 2188 to 2812 DAMAGE.
#showtooltip Blood Boil
/cast Blood Boil
/use Global Thermal Sapper Charge
/usetalents [spec:1] 2; 1
#showtooltip Bone Shield
/cast Blood Tap
/cast Bone Shield
/cancelaura Blood Tap
I also made a video a while back if that would help you any.
#showtooltip Summon Gargoyle
/use Potion of Speed
/cast Empower Rune Weapon
/cast [target=Player Name] Summon Gargoyle
Streaming - http://vimeo.com/10517226 (Best to watch it in full screen)
I hope this helps you become a better Death Knight.