At that gear level, if you're running out of mana in ZA you need to pull more mobs.
My OT is a bear, and he'll pick up one mob at most and will just stay in kitty form and DPS on a lot of pulls. I can take a severe beating having 5 pc T6 + Bulwark -- that also means I WANT to take a severe beating since I'm perfectly safe and that keeps the mana rolling in. Occasionally I will have to pot anyways during the Dragonhawk gauntlet if we get a favorable roll on the random scouts, and maybe pot during the lynx trash since they just don't hurt, but 2 pots per bear run is perfectly reasonable.
Also remember: You can always turn your back to mobs to force yourself to take damage. I use this trick occasionally.