After reading up on shaman mastery from elitist jerks, and various other web sites. I realized I was doing something wrong. What was that? Well I was playing like I was in woltk. HS spamming my mana away. I had to read, let the knowledge slush around in my head a while and then I came to a point where I could heal a boss fight and have mana to spare. Here is the secret.
I use spells very differently.
For tank healing I'll throw up earth shield and riptide before pull. Then I'll wait for the incoming damage. If the damage is low enough I can keep the tank up just by spamming riptide.
If the tank is taking a lot of damage I'll use healing surge to bring em up to about 60 - 75% health.
If the tank takes a huge dip I nature swift + unleash life + greater healing wave the tank which will usually bring em up to 75 - 80%
On situations where aoe damage is being applied; I usually will healing rain the melee and try to drop at least on healing surge on each ranged with my self standing in the healing rain with the melee. If somebody is still taking a bit more damage than the others I'll also riptide him.