Problem generating threat 10man+

[Wookiefoot]

It seems like my tps is a lot lower than a druid,warrior, or paladin's. Whether it is 10 man or 25 man. I know my gear isnt BiS but i do work hard to keep it maintained to the best of my ability.

I have two specs. Blood (for single target threat - which in most cases i am way above the raid.)

and frost - which i use to aoe mobs.

here is a link of my armory The World of Warcraft Armory (http://www.wowarmory.com/character-sheet.xml?r=Daggerspine&n=Wookiefoot)

I know my rotations quite well for both specs.

My question is am i gemming wrong? Should i be using more strength?

any help i would appreciate!