Nap struggle

I’m trying so hard to get my baby to take two longer naps during the day, he’ll wake up @ 7, take a quick 30-45min nap around 9:30. Another nap at 1 for an hour and 10mins, and then he would take another nap at 4-5 for an hour and 10. Any advice? The last week he hasn’t even taken his last 4-5pm nap. So he has been awake for 4.5-5hours before bed.. I feel like he isn’t getting enough sleep during the day. Sleep regression possibly?