Unsure of gender

Hi all, last week I had my ultrasound done at 15 weeks and 4 days... the ultrasound tech had difficulty telling the gender until she settled on a boy. While looking at my other boys ( I have 2) this one looks different to me. So I decided to google and I’ve read that it’s difficult to tell gender before 20 weeks do to swollen genitals or the baby “sitting” on the cord. I found a picture of an ultrasound of a woman who was also told boy around the same time I was then was told a girl at her 20 week ultrasound.

Here is a picture from my oldest at his first ultrasound at 20 weeks... you can clearly see the scrotum and penis. Where I don’t see a scrotum with this one.

Has anyone else been told a boy than it turned out to be a girl?