Why do you feel a pang of regret for those children you never had, that you always said you never wanted? Why do you feel a yearning for kids when you know they really don't fit your lifestyle or who you are?
I'm at the park, watching a bunch of kids play softball, and a gal sitting nearby asks her friend, "Ever wanted kids?" and the gal shakes her head: "Nah – too much to deal with as it is." "Yeah," the friend says, "But sometimes I wonder if I should have." "Well, you still could," her friend replies, "You're what – 37, 38?" "Just," the gal says, "But it wouldn't work. I hardly have enough time for my job with all the travel I have to do, plus keeping up with chores and all the stuff my husband wants, much less dealing with a child – and he doesn't want kids anyway." She sighs, "Oh, well."
No, not "Oh well." If you have a yearning for a child, explore it! Just because you don't want your own full time children for whatever reason, doesn't mean you can't have the joy of meaningful interaction with children. Big Brother and Big Sister organizations abound – as do all sorts of other volunteer organizations which are always in need of helping hands. You can choose to participate in a child's life as little or as much as works for you.
Children are one of the greatest joys of life. Don't deprive yourself – or a child – of love and support just because you don't happen to have any of your own.