When did 2 mean perfect?

This little rant has been preying on my mind for a few months now. Because my daughter was born prematurely we were automatically entitled to a visit from the public health nurse. It was alright, though a little useless to me as she was my 3rd child and a month old when she came home. What irked me was the phone call I got the next day. Her supervisor noticed that I'd been pregnant 6 times and did I need any help with birth control? Excuse me? I don't know if she noticed that while I'd been pregnant 6 times, I'd lost 3 babies to miscarriage. All pregnancies were planned. All children were wanted and all lost babies were mourned. So no, I didn't need any help with birth control.
My husband and I always wanted a big family. We knew we wanted at least 3 and probably 4 children. We certainly didn't anticipate miscarriage(s) along the way. We also didn't anticipate the health risk that this last pregnancy posed to me in the end.
What I did become aware of before and since having my 3rd baby was the surprise that we wanted more than 2. And odd thoughts came into my head. Was I being greedy having 3. Socially irresponsible? Unreasonable? Wait a minute, since when did 2 become the magic number? Isn't that what our society like? 2 kids, preferably a boy and a girl. I got that comment a lot too, "pregnant again, going for the girl are you?" Honestly, we would have been just fine having a 3rd boy.
It's true though, having more than 2 you get a few looks. We were out at the store without our oldest the other day (he was at school) and someone actually said to us, "Hit the golden jackpot did you, a boy and a girl", you should have seen the surprise when I told her that our other son was at school.
I don't know why our culture feels this way? Why shouldn't a happily married, socially responsible couple have more than 2 children? You know that for the first time ever our country is facing an upside down population, where the retired age is outnumbering any other age? We have a declining birthrate for the first time ever. It's funny isn't it? We have less marriage, increased birth control, increased abortion, increased number of children in a 1 parent household, increased children being raised by grandparent. What does that say about our view of family? Maybe it isn't so odd that I would be asked about birth control? Maybe the public health system doesn't see a lot of happily married couples raising their kids and taking responsibility for them? I don't know.