My son is 5 weeks old and after 4 weeks of very painful breastfeeding I decided to express instead of BF. He now has 4oz/120ml EBM every 3 hours during the daytime and 4oz/120ml EBM or formula (depending on how much I am able to express) every 4 hours at night. Since birth he has been steadily on the 25th centile. Am I feeding the right amount? At what point must I increase the oz/ml that I am feeding him?