Harry Potter first written as a girl?

So I have heard that when J.K Rowling first started writing Harry Potter, the main character was supposed to be a girl, but she changed the gender to appeal to a larger audience. I don't know if this is true, but if it is could someone give a legitimate website this information is on (not Wikipedia). I would like to use this information, if it is accurate, in an essay I am writing on the differences between male and female novelists.