Christine,
Well I went to put Marlow down at 2pm (after 3.20min A) and she laid in bed talking, sitting, walking, and fussing. After 20 minutes I went up there and laid her down, said sleepy time, stood there for about one minute and left. She was OT and needed someone to make her lay down and be still. After I walked out she fussed for another minute then fell asleep at 230pm. So that's a 4 hour A in all and I'm hoping for a nap that lasts until 4pm. Here's to hoping.
If Marlow wakes at 330pm she goes right down for her BT. If she wakes at 4pm she rolls around in her crib at bedtime but eventually falls asleep. It just takes her a bit longer.
I'm sure Sophie isn't the first baby to transition to one nap at 11.5 months so if it works for her than great! Keep a log of her sleep times the next couple of days and see how she does. I'd log all nap times, bed times,wake times and any NW or EW just so you can see a pattern. You know how that sleep deprivation will take a hold on us too and then its difficult to see a pattern or any warning signs that what your are doing isn't working.