I think I have heard of this feeling described as "passionate protectiveness," or something like that. It describes how I feel pretty well. I hold him tight and I know that I would not, and will not, allow anything to happen to him. If anyone bursts his balloon or knocks over his sand castle, if anyone spills his milk or breaks his heart, they will have me to reckon with.
Maybe there will come a day when he doesn't want me to protect him anymore. That would be terribly difficult. Until then, though, he's got himself a mama bear who will look out for him.
I still fear, though. I'm afraid I will not be enough to protect him from this evil, evil world we live in. (It never seemed this evil before I was a mother.) Yet I know the world he lives in is different from the world I hear about on the news. His world is safer, because I have already given him so much. I gave him a loving and loyal father, one I married so he would always be assured of both of us. Together we gave him a home that is always safe. We keep him close to us. We don't hand him off to a million and one people we don't trust. He will never be lacking for love. He has his father's arms and his mother's breast always there for him. He has a large, loving extended family that thinks the world of him. He has amazing godparents to count on when he needs them. He has all of his parents' close and trustworthy friends who will stick up for him.
Someday he will have to face more of this big, bad world on his own. But it will be in his own time, when he is ready. His childhood won't be taken away from him or hurried along. When he steps out into the world on his own, he will be strong and confident, because he has been loved so well.
I believe this, and that's how I ever sleep at night.