Baby not waking for feeds

Hi my 3 day old baby (was born 37+3 due to cholostatis) won't wake up for feeds at all,, my midwife said leave it no later than 5 hours before I wake him which I've been trying to do, but when I go to give him his bottle he is just falling straight back asleep and he is only taking a tiny amount of his milk and it usually dribbles out of his mouth, when I wake him again it's just the same thing he falls back asleep what do I do because I'm worried about him not getting enough feed?