In the many years I have been transitioning, I have also been losing many hairs.  Went for a haircut yesterday and agreed to be a test case for this vitamin mixture that can thicken your hair.  What can I say?  The woman that cuts my hair is beautiful.  I am putty in her hands.  Anyway, this stuff is supposed to show results in 3 months.  So, if it works, will let you know. 

I've Heard that Saw palmetto helps with hair loss... But that it might interfere with new facial hair growth too. I'll see if I can find the science behind it again. In the mean time, good luck with the vitamins! I hope it works for you.

OK, this is the best website I remember, in case anyone is interested. Goes into the science a bit to try to explain exactly how:

http://americantransman.com/2010/04/12/beards-baldness-and-whats-in-your-pants/