Don't you even want kids?

It happens almost every time. I am playing with a kid or just showing someone a picture of me and a kid and then the question comes...

Don't you want kids? 

Other times it's phrased as a compliment...You should have kids! You have so much love to give!

What's the best way to respond? I'm not entirely sure but here are some of the things I've said:

"Not by myself. I'm too selfish for that. I need someone who I can tag team with."

"Maybe some day!"

"I get to have fun with these kids and then give them back to their parents :)"

I admit that in my heart, I do feel like I want kids. 

But I also feel even more strongly that I don't need to have kids in order to love them. I have close friends with kids for whom I would give my life. A few months ago, I counted how many kids that applies to and I came up with 18! And I occurred to me that I would never have time to love that many kids if I had my own. God has given me 18 kids to love and I'm really amazed at His grace. 

So the next time I'm asked the inevitable question, it won't matter so much what I say. I want it to be a chance for me to remember, not the kids I don't have, but the ones I do.