R is 9 months and is on two naps MOST days. He's on a bit of a modified 2-3-4 schedule. But some days his afternoon nap is only 30 minutes, which leads to the need for a third nap. Any insight?

Here's his day today:

Wake up 5:50 (went to bed at 6:50 and woke to eat once at 3:45)
Nap 1: 8-9:45
Nap 2: 1-1:30

He was yawning by 12 and against my better judgment we pushed on until 1. Do you think he needs a shorter awake time in between first and second nap? Today he will need a 4 pm cat nap or else he won't be able to get to 6:30/7 bed time.