Yeah, I had a similar experience. But it’s not the lack of a monster limit that’s the problem. It’s that the monster ‘level’ ranks up based on your accumulated ‘Talent’. If you concentrate on fighting skills as much as possible and neglect everything else as much as possible you may find it easier.
Once you can beat up Flame Elementals and the like you will find that there are never enough monsters to fight. I have put in a request for a difficulty level setting though. 😀