Not sure if this is a problem or bug, but I have going through the game with a storm and balance friend, and the problem is that my storm friend about 100,000 EXP behind me and my balance friend. He has completed more side quests than me, excepting tower of the helephant and barkingham palace. We are currently in Azteca in the beginning of Mangrove marsh.
Assuming you are the same level (or close to it), there shouldn't be a problem.
There is more than enough exp to level up to max in the game.
This can have to do with exp from spell quests, battles, side worlds (Wintertusk), and side dungeons such as Waterworks or House of Scales that give a bunch of exp.
Even if you all do the same exact quests, your exp will never be the same. Azteca and Khrysalis give lots of exp, so he will catch up in no time :)
