What a great thread.
I would tell my 20 year old self....
1) your shame is really not who you are!
2) You are very lovable exactly as you are.
3) Do not get into a relationship with anyone unless you tell the person you love to dress in women's clothes and they fully accept it and support you.
4) Your family of choice is more important than your family of origin - be truthful and connect with people who love your honesty - those are your real family.
I am happy today and have learned so much and gained so much peace - even though I suffered self loathing and shame in big ways, I can see the value in the journey to today....and, at the same time....it is curious to imagine what my 20 year old would have done with some loving support.
Peace
Eve