Combined Feeding Breastmilk and Formula

Hi mga mommies! Pano po ba strategy nyo sa combined feeding nyo kay baby. My lo is almost 3 months. Usually, bitin sya sa breastmilk kaya minsan nagfoformula pa sya afterwards. And may times din na 2 to 3oz formula every 2 to 3 hrs lang sya. Kapag nagbreastmilk sya, nabibitin sya kalimitan kahit sobra tagal nya magbreastfeed (minsan more than 1 hr sya magbreastfeed). So sinusundan ko pa ng 2oz formula. Ilan oz na po ba talaga dapat sya?