It's time to stop going round and round with the "who's happier" question when it comes to those with and without kids. It's not one group versus the other. It boils down to how we define happiness in the first place for ourselves.
I didn't always want children. I know that's not the typical confession from someone who has dealt with infertility, but I married young, and resisted and resented the almost immediate pressure I felt to have children.
A primer on things best not to say to women who have been pumped full of mind-altering hormones and endured an alphabet soup of invasive procedures (ART, IVFs, ICSI's, IUI's), miscarriages and/or had failed adoptions.