HOLY SMURF! You're levels are low... like 20 levels low than normal... I'd do one of two options...

Go to the Babil tower/ Sylph cave/ or Sealed Cave and just level up there fighting the monsters. Look for monsters that summon minions and then just kill the minions while keeping the summoner alive.

Or... the extremely harcore masochist way of doing things...

Try to collect all of Rydia's summons and the Onion Equipment. She has four summons that can only be obtained from a dropped item from the specific monsters (Goblin, Cocktrice, Mind Flayer, and Bomb). Said items all have abysmal drop rates so its easy to gain quite a few levels for your characters while trying to obtain them. My party was 60+ coming out of the Dark Elf cave cause it took forever for the Cthulu wizards to drop their freaking summon item... Its tedious but I find that leveling is much easier when you set up a goal whether its waiting for an item to drop or just acquiring enough AP to get that next skill...