Sounds like your not happy healing so would recommend reroll/respec.
Yes… tanks have the most survivability. Thats why they are the tanks. At least you can go bear if targeted!
Healers are capable of way more healing output than tanks. Key word is capable.
Sounds like you just run an efficent group, or the content is not that challenging for your group.
If its a mid key or a patchwerk boss, group damage will be low. Good players will avoid stepping in fire. DK will obviously be able to rune dump death strikes before your HoTs tick or you can get a cast off. AND THATS FINE!
You should not try and snipe the tank on heals.
In those times you can and should start dealing damage! A healer with high DPS output is highly desirable in keys.
Resto Druid is a very proactive healer, you ideally want to get HoTs out before damage goes out. Then when damage comes out you can start pumping regrowths, throw tranq, swarm - really take advantage of your mastery.
I recommend to focus on doing more DPS while resto, and try harder content. I find it very rewarding to be pulling 30k-40k DPS as a resto shaman on some packs.
Why I main healer? Well few reasons. I like the feeling of control over the group. I think there is high pressure to perform well, as you are the only healer it is obvious if you mess up and cause a wipe. Poor DPS can skate by, other DPS can make up for slack in damage, and healers can paper over your mistakes if you mess up mechanics. Not so with healers. You really shine if you do well, and you are shamed if you do poorly. High risk, high reward. You might see someone say 'nice heals / good job healer' other players will take note and remember that you are reliable. The gameplay is a bit slower, you are sheparding the other players through the dungeon. You do not have to have a crazy high APM like DPS facerolling, the gameplay feels more tactical for me.
There is a very rewarding feeling if you can save a run with a clutch move.
The only meters that matter for healing are the health bars.