We are going through a similar thing at the moment. My DD prefers her long nap in the morning for 1.5-2hrs but only wants a short nap in the PM over the last week it has been 45mins
but i am working at getting her past this and i did the other day using W2S and she slept for 1hr15mins (much better )
So if you are happy with a shorter PM nap and longer AM nap then that is fine, perhaps try and extend the morning awake time to see if he will sleep longer for you again. What is his awake time?
Generally my DD is 3-3.5hrs before AM and PM nap and 3.5-3.75hrs before bedtime.