I'm playing right now and overall while I think the game is fine I'm having difficulty wrapping my head around the combat. Finding it a bit too hard atm. I did the weakest version of the Titan simulation fight at level 21 with all three divine shrines discovered and it took me 10-20 attempts.
It's tough to see enemy attack telegraphs and when there are more than one non-trivial enemies to fight it feels like a pandemonium.
Just checking but have you equipped your characters with materia? Pairing something like Healing materia with the Magic Efficiency one will allow you to heal more often (or MP Absorption paired with damaging magic will refund you a little bit of MP when the damage hits). Using the Speed Up materia also increases how fast your ATB fills which in turn allows you to use abilities more often.
A couple things off the top of my head:
Also this isn't really related to the difficulty but one piece of advice I'll give is: don't feel like you need to 100% each map as you get to it. I started off doing that and around ~60% through the game I was getting really burned out. Just do what looks interesting and you'll be fine. After you beat the game you can go back and finish any stuff you missed anyway. Damn, typing up this reply made me want to go back and play the game again lmao.