So baby will take your breast and nurse? The thing to do now is to slowly reduce the amount of formula he's taking in while increasing the amount he eats at the breast. Here's a (non-LLL) site that gives some suggestions.
While you're doing this, it's absolutely VITAL that you watch your baby's diaper output to make sure he's getting enough:
Here's a good article on increasing milk:
Have you been able to contact LLL in your area? The help there will be free
I know you said you were having surgery--get through that first, and do your best with nursing. When you're feeling better in a couple of days, you can really start working on getting the supply up and the supplementing down. Also here is another (non-LLL) link that can give you ideas on how to maintain your breastfeeding relationship through surgery:
Hugs! Hang in there and keep us posted!