Upset and possibly overreacting..

I was just visiting my in laws with my husband. While we were there his 5 year old niece kept pointing at my stomach or prodding at it saying "you're having a baby", really loud infront of his whole family. The first time she said it I just said nope I've just put on weight. Then I just tried to ignore it. But she kept saying it and no one was stopping her. I felt really upset because a) no woman ever wants to be told she looks fat b) I am most definitely not having a baby and would do anything to have one but my body isn't cooperating at the moment c) my inlaws may start thinking I may be pregnant and I don't want any outside pressure - im putting enough pressure on myself as it is. I was about to cry, but held it together. In the car I told hubby, he doesn't get it and thinks I'm being stupid because it's just a kid. I just feel upset and humiliated. How do I deal with this situation next time I see her? What should I say/do? Obv ignoring it is not working.. I don't want to be reminded of my current lack of pregnancy everytime I go there :(