Start of disc 2 is a long way off 70% dude!
I made the mistake of rushing through for the story progression on my first playthrough. I remember my best characters only being about level 20 at the end of the 3rd disc. So, SO hard. I'd grind like hell in some forest on the first disc if I were you, get 100 of every awesome magic you can with each character and junction yourself right up, then you're golden. Mess around with some cards/Diablos' card to item ability and get yourself some awesome weapons which open up the better limit breaks. Won't be so hard then!