You need to boost your crit. Chance, power and alacrity. I find keeping op members shields up and refreshing as soon as they drop off, this helps tremendously for keeping the dps of enemies at a manageable level for heals to keep up with.
Bubbling teammates that are not taking damage is Force and GCD's wasted. If you know the fights you know when people are going to take damage, so only bubble when it is needed. In "normal" fights, if the tank does their job, no one else should really be taking damage. If it's a toss between healing and bubbling, always heal, as the bubble can go to waste if no damage is taken during it's course.