First off, big hugs, I sympathise, my dd didn't sleep through on a consistent basis until 18-20 months, and after a while that sleep deprivation fog becomes too much.
A few questions: how long has this been his schedule? What do you do when he wakes at night? How long is he usually awake for?
A couple of things strike me about his routine. The length of his afternoon nap is what you would expect at his age after transition to one nap which makes me think he really is on one nap but the morning nap is just part of his night sleep.
The other thing that makes me think this is when he wakes--about 8.5 to 9 hours after he sleeps--my dd went thru this for a while. What happens then is they are transitioning from a lighter sleep in the second part of the night into a deeper sleep of about 1 to 1.5 hours just before wakeup. This can be a tough transition for lots of lo's around this age and they wake--which is why there are lots of lo's who get a very early morning bottle and then go back to sleep for an hour or so. So part of the early wakeups is developmental.
when my dd was having this problem I read about this situation in Ferber's sleep book-- which does have some good insights on sleep problems if you just ignore his recommended method of dealing with them!--and he explained that what was actually happening was that the early morning nap was actually night sleep that had been hived off. The example he gave was similar where the am nap fell very early in the morning. The timing of the am nap is important not only with respect to his wakeup time but the time your lo goes to bed at night--for lo's your son's age(if there on 2 naps still) the am nap she be at least 14.5 to 15 hours after bedtime--your son's is about 13 hours after. Ferber's recommendation was to go in when he wakes and essentially do PD saying it's still sleep time and only get ds up around 6. At the same time try pushing the am nap back in 15 minute increments until you get closer to the 14.5 or 15 hour mark.
But I think given all the night wakeups that what you do will have to be consistent with what you do then. It seems like he is having difficulty with his sleep transitioning through out the night as well, and while your main concern is the early waking I think you'll have to do a consistent approach throughout the night or else he is going to wonder why you are taking one approach for the night wakings and another for the early morning one. You want to treat it the same way to send him the message that it is not morning it IS night!
Let us know a bit more about what you do for the night wakings and we can help you with a plan.
