fatimah is her (rhaimahaAllah) name, amat'ul jabbar (slave girl of the Jabbar) is har laqab, and umm'ul khayr is her kunniyyah - amat'ul Jabbar umm'ul khayr Fatimah bint Abdullah somay'iy
I've heard imam abd al-Qadir jilani radiyAllahu anhu would have a Milad on the 12th of every month. After his demise, the tradition continued and because he passed away on 11th rabi ul Thani, that Milad became gayarhwin Sharif. Any reference etc?