So it's really hard to say on a day to day basis. The changeover to one nap takes weeks or even a couple of months to solidify. Have you read those stickies the girls popped up?
The reason I think she can handle a longer A time is because I think she may have been UT at the first nap since it was so short. It's always hard to work out what is UT vs what is OT so you have to see how their behaviour is etc. Often in the transition if you have an UT nap then the next day becomes OT and there becomes a cycle that is hard to break.
So in many cases where you cannot read the kid well (like mine), you just do a set nap and keep plugging away at it. With your LO if she's doing more than 10.5 hrs at night, I'd definitely aim for a nap at 12 with a wake time of 6. If she's having a short night, you may need to bring the nap back to 11 or 11:30 and an EBT to see if she tacks at night at some point. If she's not a tacker, then a set nap of 12 with a set BT will probably end up being the way forward.
Give it some time xx