What you are is someone in emotional turmoil, searching for yourself. *hugs*
It's not really for me to say whether you are, or aren't transgendered. And, to be honest, I tend to prefer people come to those sorts of answers by themselves, since that tends to be much more reliable than me saying whether I think you are or aren't, especially since I don't really know what else is going on in your life, or your past, which may give a clearer idea. I think maybe if it's playing on your mind to such an extent, then a good step to take is to try and make an appointment to see a therapist trained in gender issues. Someone who you can sit down with and get all this out, in confidence. And see what sort of feedback they have.
That being said, I'd like to ask you a few questions, regarding your post. You don't have to answer, but maybe just by thinking about the answers, you might get a clearer idea of the way you feel, and what that means to you.
Firstly, how did you feel when you were wearing your sisters clothes? I understand that you were confused, but did you feel anything else?
Secondly, what is it that stresses you when you think about it? What makes you angry?
Thirdly, you mention watching certain kinds of porn. What is it about that which draws you to it?
As I say, you don't have to answer, but just have a think about it.
