As Mindy said, these are the hard parts that come w/ a chronic illness... and I think about these things, too. I'm 38 w/ a progressive illness. I know my body is far "older" with all my health stuff... And I do wonder about the future... the kids (especially having 2 brand new babies).... all that stuff... the same things you mention.
I wish I had more words of comfort... but know that many of us here understand and really "get" what you are saying.
Many hugs --Tina