From my experience, it is definitely a phase with physical development, however, your A times are on the low end of an 11 mo. Hi daytime sleep is good, may need to cap at 2.5 hrs total. These can cause undertiredness and frequent and/or long nws.
To tackle the two things:
1) Practice, practice, practice, laying down from sitting during the day. Or whenever possible before bed. What have you tried besides rocking to get him back to sleep during the night? This phase will pass for sure!
2) Extend his A time by 15 mins each to aim for 4 hr. So morning nap will start at 10:15. Then do one of two things for the second nap and bedtime- start second nap at 2:45 and end at 3:30, keep BT the same at 7/7:30. Start second nap at 2:45 and end at 3:45, and move BT later by 15 mins also. This depends on what kind of routine works best for your family, and ultimately how your son responds. I'm inclined to suggest ending nap at 3:30 since avg daytime sleep around 11/12mo is 2-2.5 hrs.
Here is a link to what happens in the months before a baby drops the second nap. NOT saying you're there, but I found it helpful to figure out where to place his second nap and what effects there are with 2 nap routines.
From 2 to 1 nap transition (10-12m and older)What do you think?
