Ultrasound help

Samantha

I had an ultrasound done at 14w3d at an elective ultrasound place to find out the gender.. she said it was a girl. I went to my obgyn at almost 18 weeks and he said it was a boy. Which is pretty obvious in this ultrasound I think.. has this happened to anyone? Also.. what is to the left of the baby? And why does my uterus look so long.