Why have more children?

I have 2 beautiful children. One son is just amazing- he's developing into an intelligent little being and my second son is full of life but he has some issues. He is 19 months and has not started walking. Perhaps in a few weeks he may with some extra support through myself and his early intervention therapist. But really what can I expect from him. He is full of spirit, he wants to walk but he is trapped in a body that isn't ready to walk. I'm trying my best to give him the proper nourishment and exercise but is that enough. I want to give him me but how.