If itmakes you feel any better, consider that at some points your life may be harder because you don't have children, i.e. in old age :-)
*pffft*The standard adage is "there are plenty of people in nursing homes who have kids who never visit" - which sounds ubiquitous, but is definitely true.
My mother worked in a series of nursing homes when she herself was in her 60s. It was an easy way to make money - taking food trays around to the patients and making sure they got the correct meals dictated by the dietitians. I visited her there often and sometimes hung around, talking to the old folks.
It was pathetic the way those poor people would reach out and clutch you, looking for some sort of tactile contact. And trying to get up and leave - even harder. These people - strangers to
me - were desperate to keep me there, talking. And the few times my younger sister brought her toddler around? Oh, boy,
that almost caused a riot. It was like showing a puppy or kitten to an animal lover - reaching out, cooing in adoration, saying "ohhhh, how cyoote! can she sit on my lap for a minute?"
I had to wonder "do those people ever get visitors?" During the week, I saw few people, even in the later hours when people got off work and you'd think they could stop by and say "hi" to their parents. Mostly, it was Sundays when the family visits occurred; even then you could see the look of resignation on many of the visitors' faces.
Nope, being old with no kids is the
least of my worries.
If I end up in a nursing home (doubt it. I favor the Soylent Green end, myself) I doubt I'll be any lonelier than the residents who have kids.
Editing to add, on a lighter note

IMO, feeling guilty that you've chosen (or been wired, as I feel myself) to be CF is like feeling guilty that you didn't become a doctor, or an astronaut, or a CPA. Having kids is a choice; a life path. Some of us say, simply, "I wanna do something else" and know that such a choice/path is what is the best, and most joyful, one to choose.