Advice please! Planned or not, it's none of your business!

My SO and I are expecting and just starting to tell people. The first questions I hear are almost always, Are you getting married? and Was it planned? (No, and no.) 
It really bothers me that people ask these questions and makes me feel uncomfortable. It's really none of their business to ask. 
Advice please. How would you handle this? Suggestions on how to respond without sounding like a b!tch?