I think if you don't have a really strong to have children, don't have them!
I did - the broodiness kicked in at 20, although I was sensible enough to realise I was too young and not in the right place to start a family. But the longing was there at the back of my mind, for the next ten years until DH and I started trying.
I had told him very early on in our relationship that I wanted marriage and children, and if he didn't then it was better we split up. Thankfully he did.
The thing is though, if I hadn't had that drive, maybe I'd put more time and energy into other things that might have made just as happier, in the end? I might have focused more on my career. If I hadn't been so busy looking for a life partner and future father for my children, maybe I'd have travelled more, or studied more, or focused more on friendships?
Who knows, really? I adore my children and would never, ever regret having them. But I can see now, in a way I couldn't in my 20s and 30s, that they weren't the only path to a happy life.