17 weeks today

Okay So I had an ultrasound today and she showed between the legs & I'm guessing I'm having a girl because I didn't see a penis , it just looked like every other ultrasound showing girl bits but she said it was too early to tell yet & that I will have to wait until 20 weeks to get an accurate gender reveal. I'm positive I'm having a girl because I heard the sex is determined as early as 15 weeks but idk if that's for every country. I found out at 22 weeks with my first and there was no denying that he was a boy lol Your thoughts?