Stubborn baby

We had a gender ultrasound at a little over 15 weeks and the little turd wouldn’t get off it’s butt. It was moving it’s arms and legs but had it’s butt pressed up against my uterus I’m guessing and the tech just couldn’t get a good angle of the goods. She tried to move the baby but it wouldn’t budge from that spot. She got one tiny view and said she thought she saw 3 lines and guessed girl cuz she said the girls are always the stubborn ones from what she’s seen. We go back at a little after 16 weeks to try again. Has anyone’s baby done this and then cooperated? I really want to know what it is and we’re supposed to have a gender reveal and I don’t want to have to cancel it. Please let me know your experience. Thanks!!