Best way to respond to unwanted body/belly comments

I’m currently 25 weeks, and in the past couple weeks have had at least one comment every day on my pregnant body. Anywhere from a harmless “Oh you’re showing” from coworkers, to someone I don’t know telling me they thought I was 9 months already. I have a history of body image issues and eating disorders. As it is I’m finding the weight gain and changes hard to deal with. I really don’t need to be constantly reminded that my belly is growing - I know it is! And yes I know people are well-meaning. I know I am growing a new life. But I don’t feel OK just smiling and nodding. Anyone have helpful or funny responses for people’s annoying comments?