formula feeding

Stephanie

really confused on how much my bby should be taking during the 24 hours hes 13 weeks old and was 3 weeks prem plus hes a tiny baby at only 10lb 5 odds and on the formula boxes it says for his age he shpuld be on 5 ounces or even 6 5 feeds a day... but for his weight its saying 4 ounces 5 times a day what should i do ??