With my first pregnancy I didn't really start showing till I was about 22 weeks, I could tell but I don't think anyone else could! I know how you feel about being worried, I was exactly the same! I think it was when I felt the baby moving that I really started to relax and not worry, which for me was also around 22 weeks, which seems on the later side, I think many people feel movement much earlier! Enjoy your pregnancy it's over way too fast!