How can I reach my full potential as a healer?

[Lyrica_Ashtine]

if thats the case then build gearwise like a SCH

Don't do this. Assuming Empressia is assuming the crit-scholar build (most popular meta).

White Mages don't need crit. In fact, it's more of a terminal disease for white mage than anything. In most cases, a crit cure will overheal for the amount you gained from the crit. In the case you use a Cure II and fully benefit from the crit, you're healing way too late and the tank might actually be dead already.

Tranquil mentioned this before:

I would say that being able to sort of have a feel for the incoming damage and the internal timers of a given fight is paramount, as this allows you to mindmap the encounter, plan for precasting, buffer tanks when need be, cruisecontrol and multitask when possible - stuff like that. To get to that point, you need to: 1) have at least some experience in the fight. 2) be of the type who analyzes fights in full in one's head.

Do those three and you will have no reliance on crit as a white mage
Do those three as a scholar and your white mage can easily pick up the damage alone after big hits (Death sentence, Bahamut's Favour etc.). Allowing you to do other things.