After reading several comments and doing more testing, it has come high time to admit it; I have no fucking idea what I'm doing. My old magic system was linear, really linear, which I falsely equated with balance. In that system, a level 21 Wizard is still casting the same magic missile spell as everyone else but dealing 1d4+10 damage. Kind of boring.
The spells themselves were also boring. They were meant to be general, broad, perhaps even a bit bland to let players design their characters in the spaces between. But I see now that we can afford to be exciting and bold.
I've decided to rewrite my magic system. The fluff of the old system is still good, but the magic system itself needs to go.
Rewritten Lite-Vanican Magic
Wizards understand and feel deep layers of meaning in their magic. Magic is wishing, begging, demanding, imagining, forcing and self-deluding thought into power and action. Magic User tomes are written with Glyphs, each one representing a complicated emotion or mental image, with hundreds being required to prepare even the most basic spell. Wizards, at least in academic institutions, are ranked by the highest level spell circle they can cast, which is also their name.
Spells must be prepared using either a Spellbook or a Spell Aide.
Wizards have spell slots. Filling a spell slot takes 1 exploration turn (10 minutes). Magician characters begin with 1 spell slot and get 1 every even level starting at second level.
If you cast multiple copies of the same spell at once, you empower it increasing its effects. Spells cast burning one spell slot are first circle. Burn two copies of a spell for second circle. Three copies for Third circle and so on. You can cast any number of spells per day.
Now the only problem is I have to rewrite every single fucking spell.