Pregnancy showing after 20 days?

one of my best friends went up to his dads in another city for christmas. while he was there, he and his ex girlfriend had . now its the 13th, only 19 days later she says she is pregnant. she sent him a picture and she is supposedly showing. ive never seen him freak out like this. now i understand she is small, shes about 5 4 if even that. but it just seems unlikely that she would be showing this much already. it looks like an inch or two of growth but i really cant tell. this is the only picture of her i have to go off of but....it looks more like she just pushing her stomach out...idk. maybe im clinging to false hope but i also suppose it could be someone elses? ive never met her but she seems a little promiscuous...so i guess my main question is how much would a typical small girl (age 16) be showing after 17-20 days? illupload the picture soon i just want to get this posted