Hi there
It almost sounds like your little guy is getting ready to switch to one nap (don't worry it can take a looooong time before this happens). What I would start to do it limit his morning nap which will give you a longer pm nap. As you transition to one nap the morning nap will get shorter and shorter which will bring the pm nap a little earlier. This will give you slightly longer awake times as well.
Looking at your schedule I would try decreasing the am nap by about 15min since it looks like on average he gets 1.5 hours.
6 awake
9-10:15 nap
1:15-3:15 nap
7 bed
If you think he can handle the 3 hours awake time then I would stick with that for now. You might find as you shorten the am nap he needs a little less awake time before his next nap.
Another thing I was thinking about is maybe you need to stretch the awake time in the afternoon before his second nap. The only reason I say that is because it would be almost 4hours before bed from his pm nap. Some LOs are fine with that, but it could be making him a little OT by the end of the day.
Not to confuse you any more (lol) but these times could be reversed. When switching to one nap some LOs do better with a short am and long pm nap while others do better with a long am and short pm nap. It is really up to you which one would be best. If you think he prefers the longer am then you would let him sleep as long as he wants in the morning and then start limiting his pm nap.
If I have completely confused you let me know