My DD did the exact same thing at 14mo.
Before then she would be awake at 730, first nap 930-1130, second nap 130-330, down for night at 7pm.
At first I thought maybe it was being in a new house (we had moved not long before which had stuffed up her settling at night) but once we changed to one day sleep, everything went back to normal. She now goes down at 1230-1pm and wakes at around 330. It does make for a long morning but try and fill it with activities so she doesnt get too irritable and she should get used to it after a while.
Hope she settles back down soon