First I would like to say congratulations on your new baby and for deciding to breastfeed. It can be hard at first, especially when you are doing it for the first time. I would strongly recommend seeing a lactation consultant. You should be able to find one through the hospital where you gave birth or maybe through you OB/GYN. If you can't find anything there, try this directory: http://www.breastfeeding.com/directory/lcdirectory.html
LCs can help you with breastfeeding basics and make sure that you are getting a good latch. I would also strongly recommend ditching the formula. Every time you give formula instead of the breast it tells your body to make less milk. The more you nurse the more milk you make. I think that for most moms (including myself) the hardest part is being uncertain if your baby is getting enough milk. I think that we all tend to doubt ourselves and I believe that is why many moms quit breastfeeding and switch to formula. Here is a chart that I copied from kellymom.com:
IS BABY GETTING ENOUGH? -- QUICK REFERENCE CARD
~~~ BIRTH to 6 WEEKS ~~~
WEIGHT GAIN:
If baby is gaining well on mom’s milk alone, then baby is getting enough. A 5-7% weight loss during the first 3-4 days after birth is normal. Baby should regain birth weight by 2 weeks. Once mom’s milk comes in, average weight gain is 6 oz/week. If these goals are not met, call your lactation consultant. More on weight gain.
WET DIAPERS: 5 - 6+ sopping wet diapers per day (after 1st week).
Expect one wet diaper on day one, increasing to 5-6 by one week. To feel what a sufficiently wet diaper is like, pour 3 tablespoons (45 mL) of water into a clean diaper (if baby wets more often, then the amount of urine per diaper may be less). Urine should be pale and mild smelling.
DIRTY DIAPERS: 3 – 4+ dirty diapers per day (after day 4).
Stools should be yellow (no meconium) by day 5 and the size of a US quarter (2.5 cm) or larger. The normal stool of a breastfed baby is usually yellow and is loose (soft to watery, may be seedy or curdy). More on infant stooling.
OTHER POSITIVE SIGNS: After a feeding, mom’s breast feels softer and baby seems reasonably content. Baby is alert, active and meeting developmental milestones.
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I would also check out La Leche League's website (http://www.llli.org). They have tons of information including a great forum and info about local meetings. Local meetings are a great resource for meeting other breastfeeding moms and getting breastfeeding help.
Keep up the good work. Breastfeeding can be challenging sometimes but you are doing what is best for your baby!