Hungry baby!

Mrs L
Hi, from a very tired mummy. My little boy is 9 weeks this week and for the past few days he's been wanting a bottle every three hours. He's taking between 4 - 6 oz and even when he polishes off two 6oz in a row he'll still look for another three hours later. He is on cow n gate 1st stage milk just now, Should I move him on to hungry baby milk??