You are short on mitigation. Until further notice, especially while leveling, threat is out of balance. You won't need to stack much in the way of threat producing talents and equipment to get the job done. This will change as gear changes and characters change, via patches etc,.

I would ditch Guardian's Favor in lieu of more Divine Strength. Strength will help with mitigation.

I would also drop Benediction and max out deflection. At the moment, especially until you have lots of gear, should not worry about mana. If you are taking damage you will have mana. At this point (and prolly until the blue gear starts falling) you are going to need the mobs to miss you more. Blessing of Sanctuary too, if mana become a problem.

I would maybe replace the enchants on your bracers and shield with stamina and replace the stam on your chest with def and that will help a bit.

I don't know what your servers AH economy is like, but on Durotan you can snag an "of the champion" ring off the AH for 10-15g and pickup more def, str, and stam.

At this point in the game you should get close to def cap, than stack stamina. Those are the easiest stats to get with the green gear from Northrend.

This was on the WoW forums somewhere and I just stole it:

70 490
71 495
72 500
73 505
74 510
75 515
76 520
77 525
78 530
79 535
80 540

Def cap for each level.