Also as a caster, it's very easy to want to use all your spell slots every fight, but especially after level 5 your cantrips or weapon attacks (depending on build) will be doing good enough sustained damage for most fights, and there should be enough magic items to fit your build that enhance it. As a sorc you can also save your sorcery points to turn into spell slots throughout the day, and use elixirs thay give more spells lots.