Feeding - Formula

My midwife said that my baby should feed every 3 hours. He's 10 days old. He wakes for feeds almost every 2 hours, sometimes every 2 and a half hours. He's having approx 70ml-100ml per feed depending on how hungry he is. He needs to put on weight as he lost 11.6% of his weight since birth. It's going up as he got weighed the other day but he's still underweight. Am I feeding him too often? I don't want to make him wait if he's hungry.