18, 24 and a Mad Dad. How do I convince him I'm not 12 anymore?

Your 24 year old boyfriend will understand your dad's feelings. He is just trying to protect you. Soon you'll be in college and meeting new and different people. Then you'll find out if all this turmoil is worth it. I'd suggest you be patient. It is true, if it's the real thing nothing can tear you apart- not even time.