Pathfinder 1E Balance throughout the game line?

[Dragonsbane]

I use just Core Rulebook and Advanced Players Guide, and then add in extra spells / feats as things the players find via books, tomes, or teachers. This way it limits things at first until I know the party. I also add PRCs from many sources, but often tone them down a little.

My game balance seems ok. Players have casters, so do I. Players have healers, scrolls, potions, so do I. Nice and balanced.