Gender ultrasound??

So this was at 17+3 & my doctor did the ultrasound herself & seemed to have had a little trouble finding the gender but sounded confident when she said she was 95% certain it's a girl & she'd be shocked if she was wrong.. I see the one leg stretched out & the other bent but how on earth can you tell if there's a little penis or vag there? It looks whited out by the butt area. We already did our gender reveal & all but I'm so nervous she is wrong!! 😳