20 week scan gender obvious

We didn’t want to find out whether we are having a girl or boy, but went for our 20 week scan and the sonographer said she might tell us to look away at a certain point. She scanned the front of baby’s legs and I could see white testicles. I’ve read that girls can be swollen but surely not that much?! I feel disappointed that I’m now 99% sure it’s a boy and wanted to wait for the surprise. Has anyone else thought they’ve seen testicles and been wrong?