No milk to breastfeed

Hi ladies I had my baby on Tuesday afternoon and I had a c- section and since then I’m struggling with breastfeeding. I only have some drops of milk and I’m really upset because she is always hungry and she is crying. So yesterday the midwives recommended me to start formula but they told me to breastfeed her first 20 minutes on each breast and then give her the formula(50 ml). I’m a bit worried that she is not getting enough food . Any similar experiences ? What do you think I should do? I’m really upset I feel like I failed with everything, first I had a c- section and now I can’t breastfeed because of the c-section and my baby is starving. I can’t stop crying.