Everyone here gave you a good answer. Cindy James gave you a great answer.
You are young. You are thin. You are enthusiastic. These traits bode very well for your transition. You should be able to "rock your own world" and do an awesome transition! Heck, I kind of envy you! I was your age in ... hold your breath ... 1974/early-mid-1975! (Good Lord, Mrs. Calabash, NOBODY is THAT old!) The Renee Richards era. I would have given my left nut (... and my right one too! ...) to transition at 19!!!
Anyway:
When you start your hormone replacement therapy, should you decide to actually do that, I would recommend that you start working out (Any time is a great time to start doing that!) mixing anaerobic (weights) with aerobic (sports) exercise. BOTH are necessary to be buff and toned.
I was extremely buff ... before hormone replacement therapy. Now, I'm losing that. Of course, age is a huge factor in my case. No one can stay the Hand of God. However, I have committed dietary sins celebrating my transition and my move (Pacific Northwest)!
Looking at your picture, you are a genetic ecto-mesomorph ... meaning you are WAY blessed! Common Sense: "Eat less; move more." That's weight management in a nutshell. Of course, eat for taste AND nutrition and moderate junking out.
Rock on!
Your transition will slam! I just think it will!
Lacey Lynne