I breastfed for 12.5 months, without a drop of formula for DS, following my 36-week c-section. DS lost weight, a lot of weight, in the hospital after he was born, and we were VERY VERY pressured to just give him formulas/bottles. He was awake and alert often, wanting/trying to nurse, and having plenty of wet/dirty diapers so we refused and are really glad we did. A lot of people get into the trap of supplementing in the hospital with formula (sometimes I am sure it is necessary but in our case it definitely wasn't) and their supply often never completely recovers. I recommend you keep track of diapers and nursing times in the hospital, just so if they do pressure you, you have that to back you up. They gave me the worst advice that he should only be eating every 3 hours for 15 minutes...uh, no....he needed to eat every 2 hours or so for 45ish minutes. Keep in mind that their stomachs are teeny tiny early on (the size of a marble) so they do not need to get a lot to be just fine. You have likely already been leaking colostrum in pregnancy-that stuff is very calorie rich and your baby only needs a little bit to be full before your milk comes in. Nurse as often and for as long as the baby wants, as soon as possible. Lots of skin to skin time with the baby on your chest will help your milk come in too.
They do not like for babies to lose more than 10% of their birth weight. However, when you have a c-section, you are given fluids before the baby is born and that adds falsely to their weight, some of their weight loss is just from that. DS ended up losing 11 or 12 % of his birth weight (which earned us an extra day of being stuck there) largely because their crappy advice, once I fed him as often and for as long as they wanted, he started gaining like crazy and we never looked back. Our pediatrician (who doesn't do hospital rounds or else our experience would have been a lot better) told me that their daughter lost like 13-14% of her birth weight while they were waiting for the milk to come in...they let them leave only b/c they were 2 ped's, and their daughter successfully breastfed without supplementing for over a year. So anyway, don't let it freak you out. The baby will definitely lose some weight at first, it is normal and not a sign you need to start supplementing. If they do make you supplement, try pumping and giving the baby breastmilk before formula.
Try to avoid nipple shields if you can, yes, they make it hurt less but they can cause supply issues and they baby may not get as much milk/colostrum when you use them. My hospital had lazy lactation consultants who preferred to just give new mom's nipple shields instead of helping them actually learn to latch the baby without it. Nursing actually got a lot easier once we figured it out without them.
Good luck! I am so excited for you!
Me (29) DH (30)
#1-Olivia Caetlyn-9-28-09-9-28-09, 23+2 wks, emergency classic c-section, class I HELLP, IUGR
#2- Lucas Oliver (rainbow baby)- April 2011, 36+2 wks, HELLP and pre-e free! (lovenox and LDA pregnancy)
#3-Matthew, late October 2012...mostly normal, 37 wks, (lovenox and LDA again)
My blog: http://www.butterflies-and-rainbows.blogspot.com/