Amy's exact purpose as part of the group is unknown, she has all of Rumy's qualities but not the great future. Maybe she is the group's mascot.
Amy's voice actress is Chieko Honda. She is also in 10 Little Gall Force. Her other Gall Force role is in Rhea as the scavenger-survivor Mitty. Interesting tidbit: In a recent DHP release of Oh My Goddess!! called 'The Forgotten Promise' the artist/author pays Ms Honda homage by naming a character after her.