16 weeks and no bump ?

Hi! So I’m 16 weeks pregnant and still just look normal.. I had a bit of a belly before getting pregnant, but nothing over weight (if you google thick girls that’s exactly what my body looks like) and I’m kind of concerned as to why I don’t have a bump? I saw my midwife last week and there was a strong heart beat so everything is ok with the baby.. I’m just confused how girls a posting pics at 16,17 weeks with these noticeable bumps and I’ve got a flat stomach???