I found around this age I had to switch (actually even earlier than 12 months) over to the short morning nap and longer afternoon nap or my DD would NOT take an afternoon nap any longer.
You can try that OR if you always get such a nice good long morning nap, you can try to push it out a bit later and at the same time push and also cut the afternoon nap. Again, I found that 3 hours of naps began to be too much for DD at this time, so cut to 2.75, then 2.5, then 2.25, then 2, by trimming one of her naps. We trimmed the morning until it was gone and we just eventually had one around noon.
One idea is:
7-wake
10:30-12:30-nap
4:30-5:15-nap
7/7:30-bed (or something like that)
We did something like:
7-wake
10-nap (cut shorter over a period of time, stopped for awhile on 10-10:30ish)
1-3ish-nap (slowly moved later until I cut the morning out)
7-bed
It was a lot of trial and error...esp. figuring out A time after a cut nap and A time before bed. As she got older, A times grew and bedtimes got later and later to fit all the napping she needed in one day before she could handle just one nap.
It's no fun.
You should join the 2 to 1 support thread.
