Lack of supply (Breastfeed mom) Urgent

Hi, My wife try pump and in the same time she feeding my baby with another breast. Result from pump tuh she can gain around 2-3 oz. But its different kalau pump both sides in the same time. Nak dapat 1 oz pun susah. Saya tak faham pasal ni boleh berlaku like how is the logic behind. Boleh bantu bagi pandangan or nasihat tak? Lagi satu, almost 3 months wife just bagi direct feed. Next month baby nak masuk daycare. Dah try 1 week utk bagi botol tapi struggle. Baby macam dah tak serasi. Apa boleh kami buat yaa utk this situation?