It's important to look beyond their behavior at home. It's helpful to remember that at this age, they will most clearly show the lessons they have learned from you NOT with you, but with their friends. (I learned a powerful lesson about that from Amos' daughter.) With you they will be focusing on getting a sense of who they are apart from you, and it's messy. ("Shitting the nest.")
If they are letting you close enough to see that they treat their friends well, that's an excellent sign that they are becoming just the sort of young adult you'd like them to be.
If, though, their peer relationships are poor and there are concerns about substance abuse, etc., Morti's advice is very important and you may need to think about learning some intervention skills.
In any case, yes, you should have a life of your own, but not 24/7. They need you at this age, and don't usually know how to ask for what they most need from you. (They need a parent not a friend.) And if they don't get it from you, they will tend to seek it elsewhere, not always in the best places. This is the time when it's most tempting to give in to any co-dependency you may harbor, and be their pals. But it's not a good thing, for them or for you.