Anyone think it's possible that Leia is remembering perhaps a foster mother such as Bail's wife? Perhaps she wasn't told at all about her heritage and untill the end, believed that she was not adopted. After all, she is Leia Organa, not Leia Skywalker. Luke wading around in some desert in the outer rim having an idea of his heritage isn't all that dangerous. Leia running around as a princess and fighting the empire is. Does it specifically state anywhere in the films that Leia knows that she is an orphan? In this case she could remember a "Mother" that was beautiful, sad, and dead that was not Padme.