Yes, I think Miss Bates is a little too used to her own company - I don't know how much Mrs Bates actually speaks. She never actually speaks in the book, so I was thinking Miss Bates mostly has to speak for the both of them to keep herself sane in her effective solitude. Also Miss Bates I think is so restricted in society and so little excitement, that she must make a big deal of everything in her life, thus the minute by minute account.

Perhaps her inscessant talking helps her not to have time to think about her unpleasant situation of genteel poverty.