Ok first of all, stop with the asking to become every magickal/mythical female being you can think of.
Secondly, there is no spell to change your gender. While I can appreciate the whole " trapped in the wrong body " thing....magick is not going to solve it.
There are numerous people who feel like you do. Instead of looking for the simple easy way out of the problem they have with their physical self, they do something about it. There is dressing to be the role, and of course surgery. The last is a long process that required years of doing the first suggestion.
I'm sure you understand that even with the options provided to you, you will never truely be a female. If that is the issue that you have with it, then you need to seek counciling to work on the issues you have.
Magick, will not solve this.