Hello.

Yeah, you are severly under leveled. FFXII requires you to do some serious grinding before you can progress in the story line around then. You need to be at least level 32 to make this easy to manage, i reccomend around level 35.

For gambits, you need the obvious, remove poison, remove confusion etc, also consider buying a full set of new weapons(keeping always updated with the nearest shop is a requirement.) I advise the thunder spear, as it will destroy the enemies in here. I had my entire team using the flame sword, the best shield that reduces ice damage by half ( needed for the last boss in the shrine) and the thunder spear on my main dps class. Use a mage who focuses on healing and have everyone use area healing spells. (cura) I also reccomend your entire team has at least the +200 health bonus, should be close or have the +500 health one on each character.

Remember this is a guideline, and can be beaten without this, but the game gets tough here. (the shop in the previous area, the ice path, has all the weapons and  gambits/spells you need.

Hope it helps. the grind sucks, but its needed in this game.