I'm not sure how it is leveling but starfall at 120 is not optimal to use unless there are 7+ targets. You just tab/dot. the reason this probably works better at higher levels though is Sunfire is already aoe and moonfire will apply the dot to another target if talented.
Your rotation seems pretty accurate. They don't start pumping really good dps until you get the azerite traits for streaking stars at 120.