It's ok to have trouble there. Use your airship to go to the town that has the Mythril items. That should help you. If Cecil is ineffective I would have him cover Yang since his def sucks. At this point in the game I usually nuke the foes outside Tororia with powerful lev3 spells and then go into town to heal when Tellah gets low on mp. That should get you a few levels before you go into the dreaded no metal cave.