Thanks for playing. You can actually change spells in the dungeon. Just go to your spellbook, change things around, and rest to regain spells. You are right about the AOO's though. The best way to survive right now as a Wizard is to cast Shield and Chill Touch, both of which do not provoke AOO. In the future, there will probably be others to join your party at an early level, and I may possibly add a 5ft step, so it will be less of an issue.
Also, there should be additional info the UI so you know which spells provoke and which ones do not. That is actually a new rule in Pathfinder 2e. IFAIK, this is the first video game to use those rules, and there is still a lot of experimenting with the implementation.