A boy or a girl?

So i had my 18 week scan a few weeks ago and asked the sonographer to write the sex down on paper and my sister in law could bake us a cake with the colour inside of the gender of our baby. Now, shes a bit of a bitch and didnt want us finding out the sex at all... and when i cut the cake it was pink. I am getting a growth scan soon and will ask to confirm it is a girl.. but i wonder if perhaps it is a boy and shes done it to "surprise us" or if the scan could have been wrong. Or am i crazy? Heres all the pics i have. I also have 4 girls.