This is normal. Especially if your college doesn't have a regular type of campus where everything's self-contained (I'm guessing this since DePaul's in Chicago).
It's also normal since it's not just you or your pledge class that is new - EVERYONE is new since you're a colony. It's hard to feel bonded to a group of girls when you've only known each other a couple weeks!
Search on "colony" under the Recruitment and Greek Life forums - there are quite a few colonizing/charter members on here and I think some of them have had the same feelings as you.
