Routine and breastfeeding

Exclusively breastfeeding mamas - how do you manage naps in babies younger than 8 months old?

I'm struggling with working out how much sleep to give him during the day. He was prem so the sleep guides have never matched his behaviour.

He always wants to nap at around 11am and 4pm but if I let him nap at 4pm for too long he doesn't go to sleep before 8.30/9pm.

He's 7 months old but like a 4 month old.

He naps downstairs or whatever room I'm in as he doesn't feel safe and won't sleep alone in a room.

I'm hoping now we're weaning to solids we'll get into a better routine but I'm struggling with naps because of the whole on demand/hungry baby thing x