What is the major you are looking at taking? I had no idea what I wanted to do going into college and it turned out to be 4 of the best years of my life. Just because you're unsure of a major isn't a good reason to not go to college at all. You'll have plenty of time and opportunity to switch majors and figure out what you want to do while you're there.
As for the peace corps, my only advice would be, be sure you understand exactly what it is you are getting into. Two years can be a long time if your placed in a tiny village in Africa with little to no electricity and a hole in the ground for a toilet. I've know a couple people that have done it and it is a life changing experience for sure, but just be totally 100% sure that you're ready to be on your own in the third world for a long time. Too many people go and then have to leave early because they can't handle it.
Personally, I would probably recommend college for someone at your age. You can do the peace corps after school if you want, but you only really get one shot at having an undergrad experience with people your age. If you come back to college after you're older, it wont be the same. Best of luck with your decision and I hope that it works out for you!