M.P.
Around the 1 year mark my son was doing the same thing. I think my doctor told me to just go with it because he was adjusting from two naps to one. Some days he needed more sleep and some less. It stinks for a couple of months because they won't be on a good schedule, but then they settle into that one nap in the afternoon and he has been steady with that for probably eight months now. Good luck!!