Mistaken for being pregnant 😱

So I work in retail and was serving a customer and she asked me if I was pregnant, thanks to my worldest most painful period last week I'm pretty sure I'm not pregnant. I was wearing a loose waterfall style cardigan so she must've been looking pretty hard. I know I've put on a few pounds at Christmas but wow that made me feel so fat. Has this happened to anyone else? How did you react?