How scared should I be about DPS?

[Shurrikhan]

He's correct. You should be focused on three things, in order:
1. Not dying
2. Healing
3. DPS

This is true. That said, I've consistently seen people improve far more quickly by working backwards from the final goal (dps).

As a healer, you shouldn't be thinking "When can I dps?" Not only is it the overwhelming majority of GCDs, but also tends to feel more ambiguous in such terms.
Within a given window, the question should be "How much damage will I have to undo?" (This will depend on your cohealer, tank, and idiocy of any and all players among AoEs only if such would otherwise kill them.)
Likewise, you shouldn't be thinking, "When can't I move?" so much as "Where do I need to be next?"

[Vyriah]

"When (or, for how many GCDs over this time) can't I dps?"

When you end up with phrasing as ambiguous there is sure something wrong with how you see the game. To me there's two only moment I can't DPS : I'm dead or the boss is impossible to target. Outside of this, I can just press that Stone IV/Broil II/Malefic II all I want.
More likely it's from "when can I DPS ?" to "how much do I have to heal ?" that will land you better success. Healing isn't just casting, all classes have a lot of OGCD now so it isn't really strictly about casting heals vs casting DPS. Planning ahead is much more important than landing two more cast, wich is only a matter when you know the fight perfectly and try to get a better performance.

And all this vary depending and the other healer. No only depending their performance but more simply with how they use their CD.

[Shurrikhan]

When you end up with phrasing as ambiguous there is sure something wrong with how you see the game. To me there's two only moment I can't DPS : I'm dead or the boss is impossible to target. Outside of this, I can just press that Stone IV/Broil II/Malefic II all I want.
More likely it's from "when can I DPS ?" to "how much do I have to heal ?" that will land you better success. Healing isn't just casting, all classes have a lot of OGCD now so it isn't really strictly about casting heals vs casting DPS. Planning ahead is much more important than landing two more cast, wich is only a matter when you know the fight perfectly and try to get a better performance.

And all this vary depending and the other healer. No only depending their performance but more simply with how they use their CD.

I meant to imply quite heavily that those were the same thing. How much do I have to (do something other than DPS) --> How much do I have to heal? I should have done another pass over for semantics.

Thank you for the reminder. I've reworded for precision while trying to maintain brevity.