Sad about gender

Yesterday i had my 12 week ultrasound. And the ultrasound said that she's 85% sure that baby is a boy. She said she could be wrong because I'm exactly 12 weeks.... I'm honestly upset. I have 2 boys already and I had the strongest feeling that this baby was a girl. I am extremely happy baby is healthy. But just a little sad that this is my last baby and it's a boy....