Hi there, yes most LO's do a shorter A time after the CN and to bedtime, especially those with long days from EW. There is a big jump in A time between 5 - 7 mths so it's not unusual for her to protest if she's not tired.
If she's at 2.5 hours A time, you could try:
Awake 5:30
Nap 1.5 hrs @ 8 - 9:30 (A = 2.5)
Nap 1.5 hrs @ 12 - 1:30 (A = 2.5)
CN 45 mins @ 3:45 - 4:30 (A = 2.25 - shorter A time so should naturally produce a shorter nap)
Asleep no later than 6:30 (A = 2 hrs)
When she's doing this with reasonable success, you can start to push out the day, which will mean the CN will be dropped between the 6 - 7 mth period. You would push her morning A time bit by bit, and shorten up the CN.
We had a nightmare with the CN - we'll call it our 4 - 6 month CN fiasco - but by pushing out the morning we got there in the end. There was a lot of bad OT so whatever you can do to avoid it I would do :-)