No worries OP - I had a horrifically difficult time healing through Titan Story Mode when I fought him and an even worse time with Garuda Story Mode. Those battles are intended to be pretty difficult. Titan thankfully has a pattern rotation so you can just memorize it pretty quick and then you'll laugh your way through it. And as long as your party stacks together during Titan's Geocrushes (where he jumps up and knocks down part of the stage), you can Medica the whole party and get a fairly decent heal on everyone.
Trust me, struggling through some of these doesn't make you a bad healer. A bad healer wouldn't learn from problems, and you're clearly attempting to learn.
And while later content will get more difficult, you'll thankfully have way more tools to work with. White Mages get additional buffs and stuff we can use to make our healing better and help our mana management as we get closer to Level 50. You'll get Shroud of Saints at Level 38, which will grant Refresh for 15 seconds and help restore some of your MP (around ~500 MP. It's about ~1000 when you obtain Enhanced Shroud of Saints at Level 48.) and at Level 40 you'll get Divine Seal, which will increase your healing potency by 30% for 15 seconds. (Super useful when people are taking a ton of damage.)
Another thing to keep an eye out for is make sure you watch for when you get Freecure (it took me forever to notice when I had Freecure up because I rarely paid attention to it, now I notice it every time.) Freecure is the main reason to use Cure as your main healing spell and only use Cure II situationally, since Freecure grants you a 0 MP Cure II. Since Cure II is a big MP sap, this will help with mana management.
Also - using Medica is helpful, but make sure the party needs it before throwing it up - you can run out of MP super quickly if you spam Medica too much in a fight (which I've totally done!) Same thing with Stoneskin - it uses a lot of MP and should really only be applied at the start of battle to mitigate healing right off, don't worry about reapplying it.
And feel free to keep an MP restoration item on your hotbar. I always had Hi-Ethers set in one space so that I could easily use them if need be. They can come in handy if you suddenly find yourself running out of MP.
As you get further in the game, a lot of this will become more second nature to you and a lot easier. You'll also likely find yourself not following these suggestions as strictly either. You'll find ways of healing that work for you better. Don't give up though!![]()