Hey Karen, 
Fear when starting the journey is normal.  I think that the hardest part of transitioning is self acceptance first, then acceptance from family and friends.  As for not transitioning, I think there are quite a few of people that continue to remain on HRT for a long period of time without choosing to go through a social transition.
I'm in my 30's, started HRT 3 years ago, had ffs, no facial hair, 5'7, 138 lbs, etc., and still live as a guy even if I can pass.  Mainly because HRT was enough for me to dissipate most of my dysphoria.  I think some may have stronger inclinations but I think it's very possible to live going further until you're comfortable.