Amy tries to recap some stuff to Arthur. We actually know most of what she's about to tell him, but this is the narrative's handy way of giving Arthur information about people that he is otherwise not really in touch with.
The Dorrits and the Gowans are in Rome.
Amy can tell that Pet is super lonely and that their house is not a home. Also, Gowan totally sucks and is a nasty, obnoxious jerk. Oh, and his painting of Dorrit is so awful that Amy is "not quite convinced I should have known from the likeness if I had not seen him doing it" (2.11.8). Ha! That's quite a slam from uber-nice Amy!
Everything else about Gowan is also crappy. He is still doing that thing where everyone thinks he married way beneath him. Also, he's still hanging out with a gross French guy (whom Amy doesn't name, so Arthur doesn't make the connection to Blandois), who is way creepy.
Oh, and – big news – Pet had a baby boy. Aw! And her parents are here. This is nice for her but creates tons of extra stress because they don't get along with Gowan.
Amy isn't going to tell Arthur about any sights they've been seeing, since he's seen them already and probably knows more about them than she does. And in any case, she mostly only has one thought about everything she sees, which is, "man, I can't believe we were stuck in prison all that time while all these beautiful things were out here!" Sad.
Amy tells Arthur that she constantly dreams about herself as a child dressed in Marshalsea rags – but transplanted into this new life. Even in the dreams she's all embarrassed about what she looks like as she comes to be with her family. (Just be aware folks, dreams = symbolism = important!)
Finally, Amy is very homesick and sad to be away from England.