Regarding sleep

My baby is 15 weeks old...He wakes up at night 3.30am and becomes active and goes back to sleep at 6am or later after lot of effort...He take his naps at 11.30am and sleeps around 2 to 3hours and takes one or two one hour naps later...

Bed time-10.30pm

How to make him sleep at a stretch throughout the night???

I am exclusively pumping to feed him...It’s very tiring for me as I couldn’t get proper sleep...Please help me out...Should I cut his naps or when I should stop taking his last nap before bedtime???