Amina Begum, alias Khair un-nisa Khanum

Per my research, she was from Georgia and not a Qajar by birth.

ref: iranicaonline.org - Fath Ali Khan Qajar
[According to Rostam al Hokama, Mohammad Hassan (Khan Qajar) was in fact a son of Shah Soltan Hosayn (and not of Fath Ali Khan Qajar). His mother, a daughter of Hossein QoliAqa Qajar, belonged to the Shah's harem. Already pregnant, she was bestowed on Fath Ali Khan for his aforementioned bravery at the siege of Isfahan. BothTahmasb and Nader (Afshar) were careful not to provoke the Qajar tribe further after the execution (of Fath Ali Khan) and they were all pardoned although some were fined (Lockhart, page 130)]