Help me come up with a response!

I get so sick of getting asked when we will have a baby or people telling us that we need a baby. I always just kind awkwardly smile, nod and say "yeaaaah..." or "mmm, one day".

I need a better response! I need something quick and simple, not too rude, but will get them off my back. I want it to be snippy enough to make them realize that they shouldn't ask that any more, but no one knows we are TTC, so I don't want it to give too much away and cause them to ask more questions.

Aaaaaand, GO!