A few things

With your camera zoomed all the way out doing mechanics becomes much easier.

In boss fights, try to be near the boss, at melee range if not slightly further so your heals can reach everyone. This goes for casters and ranged dps too, there's no reason to stand in China unless a mechanic necessitates it.

Keep your party list in a spot of ur UI where it's easy to look at it constantly and actually be able to see the fight. Move it around till you're comfortable. Seeing the party list should be enough to keep track of players hp

Lastly in pulls you don't need to heal dps unless they get really low or the mobs have cleaves, the only person who should be taking unavoidable damage is the tank and if you spend your heals on a dps that stood on an aoe or got aggro at the beginning you're wasting your resources. ogcds you get later on will heal the dps collaterally anyways (assize, asylum) and if you really must heal them, Medica 2 is the equivalent of a cure 2 on the whole party, that way you're also healing the tank.