I've lost about half of my hair and am a woman in early 20s. I KNOW how frustrating, depressing, and devastating this symptom is.
Several months ago I switched to Ortho Tri Cyclen Lo, heard much controversial research that too much estrogen can make it fall out... Haven't noticed much difference, still shedding and not sure if growing out (short hairs may be breakage). I DID hear that Yasmin is supposed to be the best for hair loss, though. I don't have insurance until Feb 2006, so I'm on what I've got till then!
As far as supplements, I am on:
Multi
Hair/skin/nails vita
echinacea
B-complex
Biotin
Also, I just started taking:
Evening Primrose Oil
Omega 3 fish oil
I heard these supplements help as well! Good luck!