As a 22 year old guy looking back, the best thing I can say for you with your daughter is to start to instill some trust. Even though she may not do exactly what you want, trust her to do the right thing. What you ABSOLUETLY DO NOT WANT is an angry daughter that goes to college. That gets messy real quick. She does need to experience life before college, as an unprepared girl is almost as bad as a frustated at their parents girl. Make the chains are there, but that they are long enough to roam.
That said, take an honest look at the guy she likes. Based on my experience, the girls parents were happy to have me date their daughters. Maybe being 6'4", 230lbs, having a good job, a nice car, and plans for the future (at the time) had something to do with that lol.