I've recently hit 80, I've been starting to do heroics, and one thing I notice is that while I accel at AoE pack tanking for the most part, my single target Threat is lacking at times. I'm not sure if this is a problem with my gear, the spec I have, or the fact that people in heavy 200-213 gear just being able to easily out threat me.
After reviewing your gear I can only surmise it must be a gear issue. In the future, ask your dps to give you a moment for you to really hold aggro on the target. This should be a slight band-aid until you can pick up better gear. Some items I would suggest are the Tempered Titansteel helm and boots, also try and pick up a Titansteel Destroyer as it will be more threat than the current weapon you have.
Other than that I think you should be fine. Just to play it safe when engaging a boss (Or any single target situation) drop DnD first, IT, PS, BS and then have the dps engage after you BS. This should allow you some time to really plaster the boss onto you.