My bb is now 6 weeks old. A few weeks ago he took 4 oz every 4 hours. I tired giving him 5 oz when he was 4 months but he started to throw up now and then so I gave him back 4 1/2oz. But now he would wake up every 2-3 hours at night and cried. If I hold him he would go back to sleep until his feeding time. Does that mean he is hungry and I should add more milk for him?