Sounds to me it might be time to move to 2 naps a day, the extended A time should help that as I am thinking she just isn't tired enough to sleep past 5am. The fact that she mostly plays happily on her own says she has been getting sufficient sleep
It took us about a month of some no cat nap days & others with a cat nap, before we totally swapped over at about 8months old.
We had some days where I had to put him down about 6pm (his bedtime with a catnap was 7.30pm) & others it was more like 7.30pm... but now we are fully on 2 naps he pretty much sleeps 7pm-7am, which he has stopped doing from about 6.0mo & the wake up times got earlier & earlier & he was harder & harder to get to bed at night.