Annie Devlin (1 story on AO3)
May-Ling Shen (1 story on AO3)
Rachel MacLeod (3 stories on AO3 [though it doesn't look like she's starring in any of them])
Cassandra (67 complete stories in English on AO3, 32 on FFnet)
Claudia Jardine (6 complete stories in English on AO3)

I'm unable to check the number of stories on FFnet containing Annie, May-Ling, Rachel or Claudia as they are not listed as characters by FFnet's filters...though that probably says something all by itself.