Overnight feeding advice

Julie
My 9 week old son has just started doing a longer stretch at night 7pm-1/1:30am between feedings. We are doing a combination of breastfeeding and bottle feeding my expressed milk. 
The pediatrician is telling me that I can go about 6 hours for both 1) not pumping or breastfeeding and 2) for him between feedings. But he also keeps telling me that I should feed him less at night. 
My thought is to let him dictate his sleeping schedule overnight and I should just start getting up to pump around 12-1 each night so I'm not too engorged. 
Any thoughts on letting 9 week old sleep longer than 6 hours overnight without a feeding?