Sono at 14 weeks

I went for a sono at 14 weeks and the lady told me it was a boy but when I come back witch will be in two weeks I can really confirm it I really thought it could be a girl has anyone been told boy then changed ? The heart rate is always low like a boy I'm carrying low I didn't get sick at all the only thing I had really bad acne witch I  never suffered from I'm happy either way I'm just curious