My son is one month today and he is 90% on Brest milk and the other 10% on enfamil Gentle ease formula. He eats about 2-3 ounces a feeding but today he hasn't popped as much as he normally does. Should I be worried ? I know he getting enough milk, I pump into bottles. Putting him in the boob he never got enough. So this way I can measure how much he gets. Anyone else had this issue or have this issue?