With my first, I had a proper bump by 16 weeks but nobody noticed much with clothes on. People started to notice after 20 weeks.
I'm now onto the 2nd pregnancy and at 13 weeks, still no show, considering I've heard you start showing earlier than the first. There's just beginning of a bump but still, I consider it flat. I haven't even gained weight at all, but lo inside is normal size for the week and healthy.