http://www.endo-society.org/_MDDocReviewFiles/Transgender%20Guideline%20(1st%20Draft%2011.17.08).pdf Bone Mass Density is not a change of bone, it's a change in the amount of the density of the bones and is a factor in later life fractures. You may get less bone accretion, but unless your parents started you on gonadotrophins when you were ten you're not going to have a much different ride than anyone else.
Your bones may stay lighter, but that is also a double-edged sword.
As for the facial changes, drop in at good FFS sites and see how many of the women there were younger transitioners who found themselves with bone-structure that revealed them more as males during mid-life.
http://php.ucsf.edu/PatientEd/MedicalCareofTransexualpts.pdfAgain, bone structure does
not change.
There are things that are helpful about young transitions and they are recommended, but transitioning young is no guarantee of better development as the first article points out. Especially read the first 35 or so pages of article one.
Now that took all of fifteen minutes.
I know you're very vested in this and I dn't want to argue. That's not the point. If you wish to maintain your stance feel free. But we've been all through this before. Your ideas are what they are and I will not respond to personal attacks. So please, if you want to be adversarial, that fine. If you just want to dismiss me and twenty years of research, that's another situation entirely.
Check the authorship of article one. Gooren and Cohen-Kettenis work with people under 19, Rach. Cohen-Kettinis pretty much exclusively. Spack is the fellow in Boston who works almost exclusively with trans-children. Those kids are well under your 19 years.