Pats, you do have all the resources, including a long marriage to your hubby to adopt. I understand you have colitis, but many times, when you don't have a gnawing emptiness anymore, like your childlessness, it gets much better. It's driven by stress and anxiety, too. (Not saying it's in your head!)
I bet Kevin would be all for it; you're not too old. I would suggest foster care, but those kids almost always come with massive emotional issues and it wouldn't be good for your psyche. You could adopt a baby overseas and not have the wait time it is here.
I really do think if you had something meaningful in your life it would do wonders not only for your depression but for your physical health. Maybe talk to Kev?
I would do anything to help, (except babysit, lol) we all would. ((((((hugs)))))))