Stop healing after you see the damage or it is too late, learn when the damage is coming in and prepare for it appropriately. If you heal 2 seconds after damage comes out, it's useless, a waste of mana, and 90% of your healing is Heal-over-time, not instant. You have to steal healing if you want your meters to go up. Dont waste mana though. When you steal-heals, you also ensure people dont fall lower in hp as easily, when people fall in HP, it is harder to play catchup than it is to play tag-a-long. This should help you alot with druids.
currently at my gear if i lay 3 shrooms and max their benefit while sitting in org they heal for atleast 2 million every time. does that make you want to use shrooms? it should.
they are changing shrooms in 5.4 so dont worry, will be easier
swiftmend enabled harmony
nourish on tank for fillers when not rly much dmg is going out.
use lifebloom to refresh lifebloom ,it costs less mana and if you use clearcast procs / swiftmend / shrooms, you never have to worry about harmony.
Check out what im doing, get reforgelite and get the 3043 haste cap which is crucial to your healing. armory me and go off of my glyphs/talents and learn to use soul of the forest, it's getting even more buffed next patch too so get used to it now as it is a heavy portion of healing gain, incarnation is great but SOTF is great for aoe heals.