Everything Dena said (or ever says - Thanks Dena) is correct!
A therapist is a great starting point. It might seem like a cop-out but you will, at some point, need their recommendations for "stuff" to happen (hormones, surgery, insurance coverage...)
As someone who has been on the Train for 16 months, I wish I started VOICE work sooner and facial hair removal sooner. For hair removal I suggest looking into laser hair removal. It's 1/10 the price of Electrolysis and you can get some great deals through Groupon too.
I don't know about your physical shape, but for me the first step, before I even got the courage to face being trans, was to lose 25 pounds (170 lbs down to 145 lbs) which naturally brought my waste in and actually gave me an hour glass shape. It took 2 years to lose that weight but 1 lb per month was easy to sustain.
Being only 19 you have a great advantage over those of us in our 40's, 50's, 60's and even older when we started.
- Deedee