Breastfeeding mommies

Kyshia.
Ok mommies... For some reason it seems like I am not giving baby enough like he wants formula too?? Mind you while in the hospital i did have to give him formula because my milk had not come in and he was so upset. Now I always offer him both breasts before I give him formula. He was almost a 9 pounder btw.. What else can I do to make sure he is getting enough of my BM?