Childless by choice?

As a single woman in my mid-thirties, I have, to this point, chosen to be childless.  If I am fortunate enough to meet Mr. Right and get married, I'm not sure that at that point I'd want to have kids.  Certainly I'm open to having step-children if Mr. Right already has children but I don't know that I am that eager to get a jump-start on popping out a kid or two of my own.

And that is conflicting as a woman.  We, as women, are supposed to want children.  My sister is one of those women who has always said that she wants a ton of kids.  One of my childhood friends wanted nothing more than to get married and have a bunch of kids.  She's now a loving mother of four kids and loves (almost) every minute of being a mom.

Don't get me wrong, I love children and am fortunate to have many amazing kids in my life.  Between my niece and nephew, my godson and his sister, as well as the children of my friends (including my best friend's three kids who call me "Aunt") I get to have plenty of kiddy time.  Sometimes that even amounts to more kiddy time then I'd like when certain friends choose to bring their children to places they're not invited to!

That being said, my biological clock hans't started ticking and I don't have that feeling of not being able to wait to have kids of my own.  And that fact seems to baffle people at best and downright upset other people.  Like I said earlier, I love children, I'm just someone who feels no pull to have kids of her own.  And that bothers me a bit.  Am I missing something?  Should I want to have children?

In my 20s, people told me that I'd feel different when I was older but now, in my mid-30s, I can't say that I feel any different.  I've been told that I'll feel different when I meet Mr. Right and that I'll want kids with him to further our bond.  Sorry, but if I don't already have a strong bond with Mr. Right then why would I want to add kids to that mix?!?!  And if we have a strong bond already, will kids really make that bond even stronger?  I've been told that kids will "complete me" -- sorry again but I lead a pretty complete life now and kids will only curtail the life I'm currently leading!

Yes, I know kids would add a whole new element to my life that I can "only imagine".  Yes, I know that kids can be amazing and that it's "totally different" when they're your own.  But I worry...since I don't have that passion for having children that my sister and childhood friend have...would I even make a good mother?  While I love the fun moments with the kids in my life, would I be able to survive the not so fun moments that are a part of life with children?  Is it really just a matter of finding Mr. Right and knowing that with him we'd be able to do a great job together raising a family?

When my sister-in-law was pregnant with my niece (her first child), I told her that, as a non-parent, I wouldn't give her parenting advise but that I would spoil her child (now children) rotten.  And that has worked out great for us.  I get to spoil my niece and nephew rotten as well as enjoy spending time with them before sending them home while my sister-in-law is guaranteed to not have one more person trying to tell her how to raise her kids.

Why mess with a good thing?  Or, would having children of my own, actually make a good thing even better?  Am I childless by choice or has that "choice" just been an excuse to this point?