I will say this: if you do have a kid, have ONE KID. You will see, when you read over the threads here, that almost every "what have I done, my life is hell" posts are from people with two kids. I am one of those people. I love love love BOTH of my sons, but having two kids was the hardest thing that ever happened. I spend my time managing them instead of enjoying them. When I had just one, it was joyous. Two was, and continues to be, very hard and had I known, I would have only had one. Even though the second is the joy of my life.
But if you are as much an introvert as you say, and you know yourself, then you really need to re-consider. Unless your DH will be the stay-at-home parent in which case you can probably swing it. There's no space for introversion in parenting. Really. The only time I get alone-time is if they're watching TV or asleep and that's just not enough.