As someone who can only grow 'bum fluff' on his face, I feel for you OP.
I've tried the vitamins and they don't work (que people going 'derp of course they won't').
It seems my body hates me as I'm now starting to bald as well and I'm only 26.
GF won't be too happy if I'm bald for the wedding photos!
I've been going grey since I was 15 and been thinning for the last few years, it's why I decided to go full beard I need to keep hold of some sort of hair!