What if you went back to longer am nap after a regular A of 3hr30, cap am nap at 1.5hrs, then 45min-1hr pm nap after 3hr30min A. Bedtime would probably be after 3hr15min-3hr30min A. So assuming 6am wakeup her day might look something like this:
6am Wakeup
Nap 9:30-11
Nap 2:30-3:15/3:30
6:45/7pm Bedtime
I am doing similar with dd2 right now but because she is older she is down to 30min pm nap. She woke earlier today because she sttn completely but I was still able to keep her am nap at the same time because she had the long sleep overnight, so she could do more A in the am. So I know set nap can work because I have been able to make it work with my dd, but the set nap only works if she has the good night sleep the night before and is well rested, yk? If things are all wacky, then I need to sort out As to get back to good sleep, then once things are settled, set those nap times if her wakeups start to vary.