I'm twenty-eight and have, for most of my life, been quite content to be unmarried and childless. For the last few years, my teenage niece has been living with me and she's been child enough. However, in exactly one month she'll turn eighteen and will shortly thereafter be running off to college.
And all of a sudden I'm starting to worry about having children of my own.
I actually wrote out a timeline at work today, figuring out where I could fit kids into my plan for the next ten years and then how old I would be when my children turned eighteen and how old I'd probably be before my first grandbaby. Bleh.
So, please, tell me when (if) you experienced this and how long it took for your sanity to return.