By the sounds of it , he could be OT. with so little naps he really needs to go down earlier in the evening. Lucky there are no nw!!!
30min naps normally mean OT, so try putting him down earlier for the first nap - say 30mins. 3hrs is about right A time, but for the first nap, A time can be shorter to get a better nap. And, the 3hrs A time really relates to a well rested baby. So if you get a 30min nap, try put him back down around 1.5/2hrs after the nap. YOu may get longer then.
Then when he is back to longer naps, he can stay up a bit longer at night time
hth