Just a word to the wise... if you supplement, your body will never make enough.
An extremely SMALL percentage of women (who haven't had breast surgery, augmentation, reduction, partial mastectomy, etc.) don't ever produce enough milk... even though many who have had those surgeries do.
The way your body works is on demand. When the baby keeps nursing after you're empty... your body starts to produce more. When their nursing slows down (or if you start supplementing) your body produces less.
Many women have actually added a whole other mouth/stomach (aka started nursing someone else's child), and their body after a few days to a week steps up to compensate.
4 other things to note:
1) Hind milk doesn't feel the same as when they "relieve the pressure"... it feels like they're getting nada... but low and behold, they're swallowing. Hind milk is also where the vast majority of nutrients are.
2) The single biggest cause of low milk supply is plain and simple dehydration. If you aren't drinking at least 2-4 liters (1-2 gallons of water) up it. Essentially, live with a giant waterbottle in your hand. The 2nd cause is stress.
3) Cluster feeding. It's annoying. It's exhausting. It's otherwise known as nursing up to 3 times an hour. Nearly all babies do it at different stages in their development. Nursing is HARD work. So is growing. So sometimes babies will cluster feed because they're too tired to do otherwise... sometimes they do it because they're burning through calories. It's also an extremely natural way of bumping up production... so when they're switching from a period of not eating a ton, to eating double or triple what they were... cluster feeding is often found in the transition. (You'll know this is the case, when your nursing times start getting reeeeeeaally long after a day or two of cluster feeding.) Also.. many babies have TEENSY tummies... and are only able to eat an ounce or two at a time. They're still HUNGRY, but their stomachs are full... so they have to wait 15-30 minutes.
4) All of this is very natural, even though it takes about 24 hours, and adding formula kind of gums up the process (making it take longer for your body to start producing more... because every time you supplement your body starts making LESS rather than holding steady) but in rare cases... the body just doesn't make enough. How to know if yours ISN'T? Dry diapers is the first sign. BF babies might not poop for a week, but they're usually wet throughout the day. Signs to follow are lethargy (awake but ragdoll limp... go to the doctor immediately), & failure to thrive.
For any and ALL questions, do feel free to contact your hospital's Lactation Consultant at any time. La Leche League is also great... but they're so gung ho they can be a little scary sometimes... but their website and their members have TONS of info, and it's all scientifically backed. You lactation consultant also has all that info at her disposal. So either choice (or both!) is a good one.
best,
R