Well thats the problem i'd say. I don't recommend that party for your first time through the game. Infact, any party without a fighter will be a lot more difficult.
I find quite easy playing on easy mode with a party of a Fi/BB/RM/WM or Fi/Th/WM/BM in that order. First timers should start on easy with at least on Fighter. Normal mode and no Fighter partys are for experinced players.