I'll bet it's nothing to do with the way you look, some people can just sense it. I knew my sister in law was pregnant before she knew. She had to be a month in. I can't say how I knew, I just did. I hadn't spoken to her in a while, but saw a pic on facebook and knew. My mother in law knew I was pregnant before I told anyone (well, I obviously told my husband, but we wanted to keep it a secret till after the first doc visit). We were camping with our in laws and I was very sick every morning, plus I had to go to the restroom every hour. I guess that is how she figured it out, but I don't know.