Well sweetie, I learned with my first that as soon as I figured out a schedule, he grew and changed it!
You need to follow her cues - you are good at catching her signals of tiredness so continue to watch and pick up on that, and put her down a little later, or only one instead of 2 naps.
I think she is ready for one not two naps - even though she may seem tired and fussy and not ready to give up her morning nap, try to let her play and kind of wear her out, instead of "resting" her for an hour at 9. Let her play hard then put her down at 10 or 11 (whenever you see signs of tiredness) and you may find that she'll sleep longer and better with just one nap instead of "resting" all day long.
(Same principle applies with eating which I have found with my skinny little boy - it's better for him to eat as much as he will at lunch, then a good afternoon snack, then nothing, not even when he claims to be starving to death, in the hour or two before dinner, then he eats more of a dinner than he ever would if he were snacking constantly throughout the day.)
And yes, it can happen as early as this. :( My son outgrew naps completely about 2 3/4 years old :( I dont remember when he went to one nap instead of two, but that sounds about the right (same) age as mine.