I ended that 19th chapter feeling perhaps a bit ashamed myself. Dickens probably express too overtly his admiration of Amy Dorrit. He wants to describe a character of pure goodness, and that's hard for almost any writer to do. But the reader should be able to see that Amy is a believable character, though not one we are likely to run across often.
There's an interesting situation here. The character of Amy Dorrit may make readers today uncomfortable (whereas perhaps many in Dickens's own day loved her), because it seems the great majority of people today adhere to a pragmatic kind of ethics different from the Christian ethics of Dickens. Many people today would say that Amy has her own life to live, she shouldn't devote herself to her failure of a father, it's like a "bad marriage" in which one of the "partners" is doing all the work & would be fully justified in "getting out" and starting over, etc. Some readers today would go futher and say that Amy is sexually repressed -- she is uncomfortable with young Chivery's romantic interest in her (marriage), and this is because she is not only small and childlike in appearance but psychologically immature, denying her own sexuality, etc., by remaining anxious to please her father; or, indeed, that she is like some sort of sexless mother, with her father as her child etc etc. However, that sort of thing reminds me of C. S. Lewis's remark about a modern critic who disliked Sir Walter Scott's Jeanie Deans (who was devoted to her erring sister), that what the critic said sounded like something from a review by a jackal of a book by a lion.
Amy's ethics aren't pragmatic. She would not say "Whatever works." She loves her father unconditionally, sorrowing over the warp in his life, but not scolding him. Perhaps, within the context of her own ethics, there needs to be a little effort to help him see that his self-pity and pretense are not good for him, etc. But the chief thing for Amy is like what the Elder Zosima says in
The Brothers Karamazov about humble love of the erring. These two, Dickens and Dostoevsky, two of the very greatest writers of the century, were kindred spirits in important ways. Amy's best friend is a ragged "retarded" woman.
Anyway, these comments could be refined -- but I want to get back to the novel. I've just read the chapter about Merdle, the master of money and slave of Society. Dickens shows him as a prisoner of his false values. The man certainly is not happy.