How?

How do you explain to a 6 year old little boy that you can't have anymore children?

Ryder was sitting on my lap just 5 minutes ago looking at a Christmas card we got last year from some friends that have 4 little boys, he proceeded to say that they have 6 people in their family. I answered with "yes, they have 4 kids,I suppose you would like to have 3 brothers?"  He replied with a yes and our conversation lead to trying to explain to him that I can't have any more children.  I said to him that he was our miracle child, because we went to the dr. to have him also like we  tried to do twice this year without success.

We agreed that even one brother would be nice, and he tells me that he still prays for a brother every night.  The tears are flowing down my cheeks thinking of my sweet little child that prays for a sibling.  Of course it is something I pray for so very often also, but thinking of Ryder doing it just about breaks my heart.  I am still waiting for my answer or explanation. I honestly think I know why God made us wait for Ryder like we did-because I couldn't imagine a more perfect child.  But this time the answer isn't as clear, yet.