Your levels are fine, what classes are you currently using? Do any of your characters have Multiheal (Sage learns it at 24)?
I finished the game in the mid 40s without changing classes at all, I had Minstrel, Warrior, Priest, and Mage. I don't remember any particular strategy, except I don't think I had Multiheal, so if you have that you should be in much better shape.
As for equipment, I didn't do much alchemy by that point, mostly just bought the most up-to-date things I could (check Upover's shops).
Yeah, with that level you can easily obtain level 50 grottoes. Go for it. It's a simple strategy, but if you don't have accessories that restore MP as you walk (goddess ring, happy hat) just buy a ton of magic waters and keep them on hand while you're exploring grottoes. When you reach the boss, just use some to get everybody back to maximum HP and MP before the boss fight. You can buy them in Bloomingdale, from the lady right by the entrance.