I'm looking for advice on how to handle this issue.

It seems like every time I go into Frontlines, we have at least 3 healers. Usually 4. And sometimes even 5.

Because my only level 60 job is White Mage, I can't change to another class. (But as soon as I can, I will).

Yet, despite having 4 or 5 healers. No one wants to change jobs before the match begins. I usually check other's information, and almost always everyone else has another job they could change to. I've asked if someone would change, but either no one does or only 1 person does (rare).

So because I can't make people change and they are entitled to play as they want, how should we play the match so we stand a chance at victory? Our damage output is very low and we die fast when ganged up on.
Running into the enemy team base is a death sentence and we often have healers who will try this on their own.

What can I say / recommend to my team to lead us to victory?