I'm no pro so you may want to wait for one of the experts though here's my two cents-
I too had a C-section and I believe a low supply (never did have a heavy letdown, not even drips) so my doctor told me to give formula. I was hesitant due to the supply/demand thing but I did the odd evening. I continued BF and let her suck on demand for the first 4 weeks and she did gain weight so I eliminated the formula. I tried pumping and practically nothing came out yet my lo is able to suck it out. I would suggest you continue but for now- feed on demand to really get your suppy going, also check with a BF clinic (or your hospital) to make sure your lo has a good latch and get her weight checked weekly to make sure she's gaining.