long feedings

Anam • PCOS, Baby Rayaan Feb 2018❤🌞, EC since birth, BLW

LO is 3 mos this week and I feed him 5 oz every 2 h usually 30oz total for the day. We've been trying to help him put on some weight. But sometimes he takes a whole hour to finish the 5oz! Is he taking so long because he's full or should we try a faster nipple?