At level 25 you haven't even hit the first mildly challenging content. Healing as a conjurer mostly revolves around saving mana, managing cooldowns in healing intensive fights and straight up knowing said fights,
because reactionary healing can be hard when the mob two or even oneshots your tank. There is no such thing as healing rotation in this game, really. Endgame encounter in this game are usually very movement intensive,
your job as a WHM is to find the time to toss out heals while dodging stuff, burstheal your tank up after big damage and keeping your party topped off.
Some endgame encounters in this game will rip you apart.