@Tamerlane
I've been to a manga/doujin convention/market all of once. Innocent enough name, "Comic City". The general merch booths were fine; pins and keychains and other things some fans had made. The actual manga... I saw 2 that weren't BL. The place was flooded with fujoshi, and I'm guessing they assumed I didn't understand Japanese, since there were a few that had their attention drawn by that interesting looking gaijin, and openly spoke about BL pairing me with Free characters.
Is it all or most women? No. Even in Japan most people aren't hardcore into manga, anime, lns, etc. Of BL fans are they basically all women? Yes. Are there a lot of them? Enough to sustain a large market. What percentage of women who are into weeb stuff are fujoshi? Don't know, would rather keep it that way.