Thank you for posting this, Philippa; it’s a great insight into your novel’s development and your own progress as a writer. What you say is both heartening and daunting. So much work! I’m really pleased you have an agent you like, one who is helping you develop the MS to an even higher level and who – by the sounds of things – shares your own ideas of what you want to achieve.
Good luck with the next stage! Or is that the current stage? Anyhow, with tackling the amendments you’ve mentioned in recent posts.