It's weird that lots of women get told how big their babies are apparently going to be. Not once was I told that Jonah would be a certain size, my dr even told me that fundal height isn't even an accurate measure on size, it's simply a rough idea of where things are and how things are progressing etc. So yeah, don't worry about what you get told, nothing is ever set in stone as far as ultrasounds and the size of babies.