If you "completed the first act" you should still be nowhere near the level cap (level 6 or 7 at MOST), so it's weird that it's already a "big problem" for you.
The game caps at level 12 (which is quite HIGH LEVEL by D&D standards) and you should hit it in the early hours of Act 3 at the earliest. Even then, there's still some room for power creep by the virtue of itemization alone. So there's still quite a lot to see there.
That said, I'm also more than a bit puzzled about people who claim that going above that was not feasible "because of the power creep".
Uh, HEY, HEAR ME OUT.... What about doing without the silly and borderline broken "tadpole powers" then?
