Breastfeeding latch

So my baby is alittle over 3 weeks and I'm just curious what it feels like to get a good latch? He was born 4 pounds 10 oz and the pediatrician wanted us to add supplement to his pumped breast milk to help him gain weight. So I was pumping exclusively and when I would try and nurse him to see if he would latch he would turn away from me and wouldn't suck at all cause my nipple was too big for his tiny mouth. Well i just tried again and he seemed to latch and he was sucking and making gulping noises... would that be considered a good latch?