When I'm in charitable mood I think well the docs have no answers for us, and so can seem brusque, and unhelpful, and likely frustrated because they can't do anything.
But then again, you do feel like lots of them were in the pub on the day they were supposed to be learning about treating patients with respect, dignity and compassion.
What gets me is you end up dismissed from their office with usually very frightening news, and no help in how on earth do I manage with what you've just told me. Many of us have ended up on anti depressants and in a bad way... some of which could have been helped right from the start with more understanding. Thank goodness for the forum, where you can get support.
NeedSupport - your dermatologist has given somewhat double standards, insisting a treatment will work... and yet if not.... No wonder you are confused.
The truth is no-one not even the very very top doctor in the entire world can make you a promise as to what will happen next, one way or the other. I know its probably against all that you think, but don't put all your trust in what a doc says... they can trot out casual phrases and glib remarks which you can latch on to and believe, and which were only that, a passing remark.
Yes the hair can grow through white, this is all to do with alopecia attacking pigmented hair. But... after some time the hair can get back its natural colour - so if you do get regrowth its not an absolute that it will be white and stay white forever and ever. Personally I'm happy with the white bits, as long as I have hair that's what maters to me.
Read around and look at the various sections, much information from the real people who know about alopecia - ie the people who live with it.