Thank you for your question. I believe you are asking about 2 different things. First, you are wondering about your past behavior and how it might relate to your identity, particularly your gender identity. Secondly, you might also be wondering whether this feeling of being “a girl inside” might relate to your identity as well.
These are complex questions, and the definite and final answer has to come from you. In attempting to provide you with some guidance, I first want to state that in-and-of-itself, playing with Barbies, putting on high heels and listening to emotional songs do not necessarily mean you are “a girl inside”, or transgender person. Some homosexuals, heterosexuals with a transvestite fetishism, bisexuals, or cross-dressers can also exhibit the same behaviors. Certainly, although it is not always culturally acceptable for some people to see boys behaving this way, it is by no means wrong. Are you doing other things that you consider different from other boys your age, or that might make you feel you should/could be of the opposite sex?
However, you also say that you feel like a girl on the inside. You are at an age where many questions might come up, where many things seem strange or uncertain, but with time, you may start to better understand who you are inside. It may take years before this becomes completely clear in your mind. You may start feeling more and more awkward trying to be a typical boy, and this could indicate you are a transgender individual. Indeed, some transgender people feel the gender/sex assigned to them at birth is a false or incomplete description of themselves, and that they should be of the opposite sex. So it is possible you are a “girl inside”, but it could also be that you are a feminine boy. Some people now don’t identify themselves as transgender individuals anymore, but simply think of themselves as a ‘feminine male’ or ‘masculine female’. These are of course just labels, and it is really up to you to decide who you really are.
If you would like to find out more about transgender individuals, Wikipedia is actually a good starting point: http://en.wikipedia.org/wiki/Transgender
In addition, here is a story written from a mother’s point of view about finding out her son’s gender identity: http://ai.eecs.umich.edu/people/conway/TS/Evelyn/EvelynI.html
Finally, there is a documentary you might find helpful, which covers the experiences of 2 young people grappling with some of the issues you are now facing:
I really hope these resources and the information and advice I have provided will help you find a way to be comfortable with yourself and your identity. Please let us know if you have other questions!
Dee, for AlterHéros