Ha Haberdashery just goes to show. It is entirely horses for courses, and life leads us down a merry old path that is entirely our own 
See the thing for me is, I don't think in terms of "I would have like to have had my first at 26" or whatever. It was all about meeting my DH - I don't think children were on my radar before I met him because to be honest - my evolutionary brain dismissed everyone else. Hahaha! I used to call him the "perfect specimen" for a while when we first got together, jokingly alluding to him being the perfect mate to give me children (Haha, thank god it made him laugh!).
So I just cannot imagine having children before I met DH because having children is so completely wrapped up "having" him too. Maybe if we'd met a lot earlier, we'd have had children a lot earlier but it's still dependent in my mind on it being with him.
And you do make your choices. I am not suggesting for one second this describes anyone else, but a girl I know - 23 - all she wanted to do was get married and have children. She loves her DH but she is not, in her words, wildly passionately in love with him. She just wanted the marriage and children and he is a very nice man who gave her that, and she foresees a nice life with him and their child(ren when she has more!). That is enough for her, and I wish her well...though I wonder about 10, 15 years down the line, if it will still be enough. I think it is because my own parents married in very similar circumstances, and I never felt my brother and I were the product of a couple deeply in love. And as it turned out, 10, 15 years later it wasn't enough for my parents anymore. Maybe that's why it was so important to me to find the man that gave me everything I could ever want in a relationship first, before children?
I sometimes think about the boyfriends I could have married, quite easily because they were very nice and I loved them. But it just wasn't enough, and though I feel like there was little conscious decision making going on about it, I thank my lucky stars that I held out and met my DH. He is absolutely the greatest love of my life, six years on and I am still giddy like a schoolgirl when I see him. I remember when we were getting married, I was reading about nice things to put in a speech and one was: don't marry the one you can live with; marry the one you can't live without. That pretty much summed up my previous relationships, and current life with DH.
I do worry a little - I'll be 32 when I have my first in September - that maybe the second or third won't happen. But then you know, who can say! A friend at work...she was 7 years younger than me and it took her a year to conceive while it took us a month. If anything I'm realising more and more it is impossible to predict how these things will turn out, and if it does turn out that we only have one....well I always be grateful for the one we have!