Quote 16
"If I'm a princess," she was saying, "if I'm a princess--when they were poor and driven from their thrones—they always shared—with the populace—if they met one poorer and hungrier than themselves." (13.33)
When she's hungry and can't take it anymore, Sara still offers to help out the poor child in the street, 'cause that's the high-class thing to do. Obviously.
Quote 17
"If I do not remind myself of the things I have learned, perhaps I may forget them," she said to herself. "I am almost a scullery maid, and if I am a scullery maid who knows nothing, I shall be like poor Becky." (8.13)
Sara has to keep her mind "rich" in order to avoid succumbing to general poverty. So, we guess you could say that she's never fully impoverished. Just mostly impoverished. Hey, it's something!
Quote 18
"I am different," she explained, "though not in the way you think. Miss Minchin does not want me to talk to the girls. Most of them don't want to talk to me." (8.56)
Sara feels awkward around Ermengarde after she's delegated to maid-work because they're no longer on the same level. But she's no different, really—it's just that people see her differently.