We have two and we are done. I will not entertain the thought of ever being pregnant again and my awesome husband made a permanent decision that it would be impossible for us to do so.
Initially I only wanted one child. Conceiving was difficult due to my intricate health issues. Once pregnant, I had so many complications and many, many things went wrong so I didn't enjoy that whatsoever. Then we had the baby and he was colicky for 3 months and breastfeeding/pumping was emotionally devastating. It wasn't until my first baby was 6 months old before I had any sort of relief from physical and emotional issues.
But, as you know, the mind can be a wonderful thing and help someone repress difficult times...and when my son was about 18 months old, I felt the pull to have another because I wanted my son to have a sibling. My second pregnancy was just as challenging as the first and my second son was also colicky (you know, after everyone always says "Oh there's no way you'll have TWO colicky babies!").
I'm done. I'm 36 years old and I cannot imagine going through pregnancy a third time, going through colic a third time, putting my career on hold a third time. Right now we are able to give the appropriate amount (and then some!) of attention to our two boys. I like that we can run a man-to-man on them and do special things and give them special time without being pulled in a million different directions. I'm not saying that parents of 3+ kids are spread too thinly; I'm saying that I am not sure how well my husband and I could dole out enough individual attention.
We have the right house for our current family, we both have great jobs that pay the bills with enough left over for savings and fun, and we've hit a groove that seems to work for our family. I always get asked "So, when are you going to start trying for your girl?" to which I reply "Never - that way I'll always get to be the princess in my household!"
Two is the magic number for our family. Some people are meant to grow large families and some people are meant to grow small families. My husband and I know what type of people we are.