I am like your daughter. I was fine then and I am fine now.
That being said, I wish I understood earlier in life the value of relationships. I learned from a mother who didn't have any friends and discouraged a lot of my friendships. She just didn't "get it" and how the world works, how important friendships are, how they mold your life. But I don't think anyone could have told me that in a way that I could truly understand at 21.
Your daughter will also likely also do just fine in life, but may reevaluate her choices later. Isn't that what youth is for?
There's nothing wrong with being a concerned mother, but she may have to just learn on her own. I hope she lives a long happy life!