Honestly, I don't think I've ever had expenses under 1200$/month (also San Diego) even when I lived with my parents.

Rent here is 400$/month minimum - and that's sharing a room or splitting a house with 4 friends. Not counting utilities.

Food budget alone should be at least 400$/month as well if you're eating a meager 13$ of food a day.

You'd be amazing if you had less than 400$/month of car expenses including payment/repairs.

Then there's everything else. Health bills, insurance, internet, Netflix, etc.