People asking when you're gonna have kids

J
What do you say when people ask "when are you gonna have kids?" Do you think it's rude for them to ask in the first place?
We have been TTC for a year now but have not told anyone. Earlier DH coworker's girlfriend asked us when we will have kids. We usually just laugh it off and say something like when the time is right but she kept going saying that "the clock is ticking" for us. We have only met her one other time so I didn't know how to take it or respond but now I wish I had said something. 
I will be 29 years old next week and AF just showed up today a week late. I really thought we'd get our BFP this month and it just upset me to have to have that conversation with her.