Time flies when you're having “fun.” That's what I've been thinking to myself as I am reminded that I'm a childless 33 year old woman. Here in New York City, my friends have taken longer than most to go on the long and exhausting journey of procreation. My married and coupled friends, though, are starting to pop them out, slowly but surely, and I'm completely mystified. The woman who is making her kid's baby food from scratch every week is the same woman I used to run into at clubs three years…