I think if you look at it rationally, no one would choose to have kids. They're hard work, a big commitment, childcare is really expensive, they wreck your career (For the early years at least, assuming you want to cut down hours to spend time with them).
I was much like you- really wasn't sure I wanted them, never felt I had a child-shaped gap in my life. My life was busy, meaningful and fun. I enjoyed my job and was keen to have a career that went places.
I hit 30 and had a mid life crisis of sorts- a panic about clocks ticking etc and dd1 arrived 10 months after my 30th birthday. I don't regret it- what the moaners don't tell you is that it might hard work, but watching a child grow up is also the most joyous thing I have EVER done.
However, while I am really pleased that we decided we would go for it, I also don't doubt that I wouldn't have missed them if I had never had them. My personal fulfilment would probably be better if anything as I have (temporarily) given up many of my own interests while we juggle very small children, childcare and work.
While I wouldn't take my desicion back, and feel utterly privileged to be watching my little people turning into bigger ones, there is a part of me that is looking forward to the point where we have more independence again to pursue our own interests. (And the money... when the wee one turns 3 we're going to feel like millionaires!!).
People who do nothing but moan about parenting drive me nuts through- and there were plenty of this who put a bit of a dampener on my first pregnancy too. It is honestly the most magical thing I have experienced. It IS hard work, but the joy, magic and fun outstrip that by miles.