Dd1 was around 12 months when her naps went all over the place - short naps, missing afternoon naps, missing morning naps and i think around this age, they are starting to make the transition to 1 nap. Having said that, she was not on 1 nap comfortably until she was 15 months (3 months later) so I think 1 nap is not enough yet...its a balance b/n letting them sleep twice a day but having 1 short and 1 normal nap. For us, shortening the am nap worked really well. She only ever slept in the morning for an hour, so I would shorten it to 45 mins, then 30 mins and kept offering it to her until she dead-set refused to sleep in the morning. By shortening the am nap, she would still be "tired" enough to take a proper pm nap. On "bad" days, when she would only take a pm nap, I would offer her an earlier bedtime so that she would not get overtired and to try to avoid night wakings. The short am nap would take the edge off a little and help her stay awake till afternoon nap time.
Let me know how it goes
Layla