Since you're not really using any Pyro stuff, what about switching in Warlock?
Needed to pull 1 point from SC (Storm Guard) to get the Warlock Armor, but I figure that it would be good as another proc to your greaters and trinket. This will also give you significantly more HP (Neddra's Strength/Might and Vitality), 5% crit, 12% damage, and possibly use Mortality as an "OH SHI!" spell. Not sure if the health gain will be more than just the normal spam rotation, though.
Someone mentioned running out of mana. Sac Life: Mana (followed by Bloom) after a fight should help that. You do lose the 1s GCD, but Opportunity procs may help offset that, making your Forked Lightning instant.
Sac Life: Damage could be used before your Withering Vine pulls to make them hit a little harder. I'm not sure if it affects the heal, though.