Feeling kinda nervous

Jaime
So I had my 17 week ultrasound done yesterday, I posted pictures to see what you guys thought I was having. Doc said girl, I said girl and some of you said girl. I just read someone else's post and they said at 17weeks and 4days they were told girl and at 21 weeks they found out its a boy!! How is that possible?? Are there tell tale signs, besides the obvious? :)