I think we subconsioualy sort of distance ourselves from getting attached because we know there is a possibility that we could lose these children and never see them again. I never thought I was attached to any of my kids until i suddenly was faced with having to terminate one of the children because of his parents, and I realized just how attached to him I was. However, I've had him since he was 10 months old, and a lot of the way he is now is because of work I have done with him. On the flip side, I had a little girl leave last week and when I hugged and kissed her goodbye, I got a little sad, but it was over once she was gone.
I think it takes us a while to grow a bond with these children and for them to become a big part of our lives. Since you haven't been open for very long, it might just be that you're not completely bonded/attached to them. I think there is always a bit of attachement to any child, whether you know it or not. Just wait till one of them might be leaving and then re-evluate your feelings lol