Aiyo, 25 weeks confirm usually quite jelas lah, especially if the sonographer pointed out clearly, at that stage genitalia sudah developed enough to see! But honestly, sometimes angle of baby or position can make it tricky, so kalau you still ragu-ragu, boleh je ask for confirmation at next scan or even book a private one if you really want to be 100% sure before beli things. My second one they said girl at 20 weeks tapi rupa-rupanya boy, so never say never!