This is a difficult subject, but it's helpful for me to know that I am not the only one grieving not having children.
Just this evening, I was out bike riding and I saw a father in the park playing street hockey with his two boys. I was glad for the father and the two boys, but whenever I see this kind of thing, it's like being stabbed in the heart.
I know this is non-related but another thing I saw while bike riding was tough too. I saw five boys in a driveway, playing basketball. I noticed the body language of one boy. He looked rather self-conscious and kind of uncomfortable. I remember that feeling well and it was miserable. I never felt like one of the other boys. I felt like I was inferior and could never compete with them. I always envied the boys who had self-confidence and didn't have that gnawing discomfort of being less than a boy/man.
Phoenix, Magellan and Monkey, I am sorry for the pain you each feel about this, but I definitely understand. It's a legitimate feeling and we do need to grieve the real loss in our lives.