Such a question, has anyone encountered it? We feed every 3 hours with…

Such a question, has anyone encountered it? We feed every 3 hours with formula, first breast milk. I can't figure out one thing, I give the breast and then the baby gets fussy that he's not getting enough, apparently. But when I squeeze my hand there comes out drops of milk. Sometimes he sleeps for an hour, I have a cup of tea and feel wet shirt, it drips milk ?then wakes up and gives it again and then spits it out and gets fussy. I can't understand, is the baby refusing the breast? Have you had such situations? Thank you in advance ????