My LO did the same thing a few weeks ago and it last for 2 wks - i thought i am not ready for 1 nap! :x Then sure as can be, she went right back to great napping 1.25-2.00hr. We didn't have anything developmental either - just a blip in the road.
The things i did change that helped:
-moved am nap from 9.30 to 10 & pm nap from 2.30 to 2.30 OR 3.00 (watching her sleep signs)
-don't let her have more then 11.5hr at night
-wake her no later then 7 (okay somedays 7.30 :wink: )
Just ride it out, she should snap back soon.
PS:
I was also wondering...if the baby sleeps 12 hrs at night, should you split out the remaining 2 hrs of sleep needed throughout the day? I hate when I over think everything, but I do!
That is totally up to you, but it is the pm nap you will keep so when you have nap problems, then i have read to keep the am nap to no more then 1hr. Hope that helps.