Pre-term baby boy, 19 weeks, gender unclear..

With the anatomy scan at 15 weeks, Jan Koning said we’re having a boy. He first saw lines, but according to him, that was the umbilical cord, and later a little penis came into view.
At 17 weeks with the gynecologist, she said it’s indeed a boy.
Yesterday, at 19 weeks, we had an extra check-up, and this gynecologist thought she saw a girl. He called his colleague in, and she also saw lines. Unfortunately, I don’t have a photo of that, but what do you think we’re seeing in the earlier ultrasound images?
On May 8th we’re having the 20-week scan, so I hope we’ll have more certainty then.
I thought from the beginning that it was a girl, just like with our first daughter. So it was a bit of a switch when they said it was a boy, but we’ve adjusted now and are busy with names.
I also have hyperemesis gravidarum, which is more common with girls, but it can just as well occur with boys.