Sophia, you are really zooming through book 3! I'm still moving through book 2 at snail speed, but I think this is quite common at this stage. I have been working on the Elgar piece for a few days, and have made a tentative start with Dark Eyes, but both pieces are stretching my skills as they include fiendishly tricky two part writing for the right hand. The Chopin piece is next, and I've briefly attempted RH notes, but I'm not ready to properly tackle it yet.
I really don't think I'll progress further than grade 2 or 3 - I don't think my old brain is up to the level of multi-tasking involved beyond that level. I foresee that complex pieces probably involve 2 part writing for BOTH hands - the thought is terrifying! I will play for pleasure at an intermediate[ish] level but not become a slave to piano.
"Don't let's ask for the moon, we have the stars." (Final line from Now,Voyager, 1942)