I guess you have to look at how much sleep she is getting in a 24 hr period..???
My DD#2 stopped having her second sleep around 14 months....
She wakes at 730am. Has 1 x sleep at 1230pm - 230-3pm. Then in bed at 630pm.
Maybe you could stretch the morning sleep to 1130am like you suggested.....hopefully she will sleep at least 2-3 hrs....by 7pm at night she would be (hopefully) ready for bedtime.
I find 'wearing' them out in the morning helps...i.e i take my girls out in the backyard, Sophie runs around not doing much, but using loads of energy....it zonks her out by 1230pm. Whereas i find if we dont do much in the morning...i do housework, she follows me around the house, she takes a bit longer to fall asleep, and doesnt sleep for as long....
Anyway, i dont know if this helps.
I remember DD#1 changed her day sleeps around 12 months of age too....which is about where your DD is now.