Increasing my milk

LosaJrTomasi

My lo will be 3 weeks on Saturday and it seems lately like I don't have enough milk for him. I think he might just be going thru a growth spurt but I just don't want to not to beagle to bf him. I currently bf him all day but when it come tonight time it seems like I don't have enough for him at all. He will keep wanting to feed and will constantly cry like there is no milk coming out. And to be honest I really doubt there is any milk coming out on that point. So when he wakes up for his 12am feeding I give him 3 oz of formula. What can I do to increase my supply a little? I have been reading about adding a pumping session but how often and when do I do that? I would love to not give him that formula at night.