Just one battle played (and won) today. I went back to the only place on the map I can currently reach where random battles can occur, in the hope I could play and bump up my stats a bit.
Killed all the baddies bar one, and got him stuck in a corner while I hit him with as many non-HP-reducing attacks and spells as I could, until he decided to attack me, and I countered, killing him. Sadly, nobody went up a level in the fight at all. I have, however, gained more JP so hopefully that might help.