I think lvl 13 is fine for act 1 from what I've heard. Kiya or someone who's actually completed the game will be of more help though.
Apparently you get better spells etc. in act 2 so I would soldier bravely on.

" Road rage, air rage. Why should I be forced to divide my rage into seperate categories? To me, it's just one big, all-around, everyday rage. I don't have time for distinctions. I'm too busy screaming at people. " -George Carlin