First off, welcome to the boards!
I have found some wonderful information and met some wonderful ladies, and I hope you have the same experience, and gain some wonderful insights on your lo!
My first instinct would be to say that he needs more A time. I know you say he is very hard to keep awake, but most babies are able to stay awake closer to 1hr 45min to 2hrs at this age. Short naps, and night wakings are signs that a baby might be ready for more A time. The other problems is that he can't go quite as long between feedings. So it may be a growth spurt as well. If he is BF however, many times they don't ever make it to the 4hr EASY. I would slowly start to increase that first A time of the day about 5 min each morning, and see if that starts to help to try and transition him to a 3.5hr EASY, and then see how that goes. In order to get him fuller you may want to try EAEAS to "tank" him up before taking a nap. So your day might start something like this
Day 1
E 8:00
A 8-9:05 (may try for another small E around 8:45ish?)
S 9:05-11 (this would obviously be ideal, and if he wakes early, try to get him to go as long as you can before feeding, and if you need to put down early for next nap to avoid OT do so)
Day 2
E 8 A 8-9:10 S 9:10-11:10
Day 3
E 8 A 8-9:15 S 9:15-11:15
Etc. 45 min naps tend to signal that baby needs more A time in order to be tired enough to sleep longer. I am also wondering is he snacking? Is he getting a good morning feed in or just enough to hold him to the 3hr mark? Being hungry could be another contributing factor to him waking up early from naps. But I think the major thing would be such a short A time to start the day off with.
When trying to extend dd's A time we always did things very very quietly - no toys, no gymini, nothing hanging over her head, no tv on, etc. Just very quiet activities - tummy time, swinging in swing (not to sleep), carrying around the house looking around, sitting on porch watching the cars, etc.
A couple of links:
Time to transition:
https://babywhispererforums.com/index.php?topic=63161.0Is my baby ready to increase his A time?
https://babywhispererforums.com/index.php?topic=84884.0Growth spurts and how to tackle them:
https://babywhispererforums.com/index.php?topic=67976.0Hope some of this helps, let us know how you get on!