Girls, who had this: "at 15 weeks they said it was a boy and showed so…

Girls, who had this: "at 15 weeks they said it was a boy and showed something like a little sausage, at 16.5 weeks it wasn't visible, the baby closed it, they said girl. Well, at 16.5 weeks I had to go for an ultrasound because there was brown discharge. I'm planning to go for an ultrasound at 20 weeks. And who did you have in the end, really? Just my daughter was on the right side of the uterus, and now the baby is on the left ?? I don't know who to believe.