Hi,
I think, next time it come sup in conversation just tell them 'We are planning to wait a few years, until we are more settled, financially independent, finished school etc. just be honest and let them know that you have a plan for your lives together. That's how I stopped my Mum from asking me all the time (married 2.5 weeks) I just told her that DH and I have a plan to buy a house, travel and then we will decide if we want to have children.