D.C.
I guess I wonder why you think your body can't keep up? Is your baby losing weight or not having wet diapers? If not, you are making enough milk. Sometimes newborns want to nurse very frequently - that is not a sign that you're not making milk. Often, it's just because the baby has a strong suck reflex and that's how she self-soothes.
The reality is that the worst thing you can do for your supply is give formula between nursing feedings. The more you nurse, the more milk your body will make - it is totally a supply=demand system. If you give the baby formula in between nursing feedings, your body doesn't think the baby is eating much and so your supply goes down.
For some tips on getting started in the early days, you can read some of the articles on this website: http://www.kellymom.com/babyconcerns/bf-links-concerns.html This might help you get started.
There are a lot of tips to increase your supply like pump after each feeding, eat oatmeal, and there are other natual supplements. But the best thing you can do to increase your supply is nurse nurse nurse.
Congratulations on your new baby and good for you for being committed to nursing!