as Annie says we will worry about these little ones every moment of our lives. I think we worry more in general because having them was not as easy as is for most people. Ergo, we need to get past every single milestone before we can breath a sigh of relief, and then there is another to overcome.
I'm sure your boy will be fine. We must remember that with DE, there is little chance for all the things to go wrong that is usually associated with our age.
I'm sorry that your clinic was not more flexible for you, but glad that you and DH are happy with just the one. As Annie says, we only need one!
So good to hear from you & hear everything is coming along as planned!