gender

im 16 weeks and 3 days and i told the ultrasound tech if she could peek on the gender & at first baby had legs crossed but some how she was able to see & she said baby looked like a boy. here are some of the ultrasounds she gave me idk if on the top one is the umbilical cord or his boy part? and how accurate can the dr be? i dont want to get my hopes up. thanks in advanced. posting anonymous because i have friends and family that are using this same app.