milk supply

Chasity

I'm looking for advice on how to build up my supply. My son is 4 months old and I work 12 hour shifts. He never has enough through the whole day and we use formula when we run out. Please help. I've noticed when I pump ever three hours at work I'm only getting 2-3 ounces. He drinks 4 ounces at a time. Picture so I don't lose the post.