My kids are grown and married, but yes, I think I tended to be overprotective at times. I tried very hard to keep it to myself but I'm sure I wasn't always successful. Our kids did have a lot of freedom as long as they were honest and we knew where they were. But I worried like crazy.
How to give them breathing space? I'm not sure really. I think if they are involved in sports then they have time away from the "eyes" of parents, they get to travel with the school and enjoy that independence. Our girls also wanted to take Tae Kwon Do classes and they really enjoyed that--but it was their choice to take them. I also tried not to grill them about things and if they wanted to talk, I just let them talk.
Truthfully, when given a choice, both girls wanted to spend time at home. They really enjoyed having friends over for movies etc. So I guess they found their own breathing space.