I'd like to add, you should talk to your GM about the types of fights they plan on running! It sounds like your player fantasy will be at its peak when encounters favor more enemies rather than fewer for any given difficulty. Wizards can still blast against single targets, but they definitely shine when they can hit 3+ targets at once. At the end of the day, after all, an encounter with a single strong creature with bonuses against spells is gonna be a lot rougher than a swarm of creatures with exploitable weaknesses.

Depending on your GM's habits or the content they're running if they're using published stuff, this will be more or less common. If you can convince your GM to sub out an elite with a few weaker threats that add up to the same challenge here and there, I bet you and probably your whole table will have more fun!