Breastfeeding help

Hey there other mommies! I have a dilemma. My daughter will eat 4-5oz per feeding which is still every 3 hours. She is 3 months old. when I pump I can get 3-5 oz per breast but she eats it all so fast, I only pump 2 times a day and when I'm trying to breastfeed she is never satisfied. Have others struggling with this type of issue do maybe 2oz formula and the rest breastmilk??