Emma,
I for one, have found that my crossdressing is really some sort of self-prescribed therapy. I find that whenever I am stressed from life or from work the thought of crossdressing grows stronger and stronger. When I get depressed, as well. I believe that when I was a child I spent a lot of time alone. When I was alone in a huge house there wasn't much to do but to watch televeision. This progressed into dressing in my mother's clothing and actually my father's suits as well, come to think of it.
I think now I find a lot of comfort in women's clothing. It still feels like an escape for me. I don't know if that makes a whole lot of sense.
I saw that you are going into nursing for mental health. Very interesting.