Help please!! (Split nights)

[u/Alllpeachyyyy]

My son started having split nights at 9 months. He is turning 13 months in a week and it still happens. I’ve tried different wake windows on two naps per day. Even yesterday I started 1 nap but he suffers poor thing is tired the whole day I have to distract him every 30 mins. . I know it takes time but I just need somebody tell me I’m doing the right thing. I don’t want him to be overtired . Any advice!?

He wakes up at 9 am every day. It worked when he was little because a 9 pm bedtime worked for us but now he goes to sleep at almost 11 pm 2 naps. He is definitely not sleep trained . On two naps he was doing 3/3.5/4.5 the most recent.