No milk or colostrum after delivery

Hello mummies,

Please help me. I am feeling so helpless, sad and defeated. I was on insulin because of gestational diabetes and because of that my labour was induced. After delivery my son latched right away but nothing was coming out. It’s been 3 days since delivery and there is no sign of milk or even colostrum. Finally the midwives started formula for the baby. I am latching baby before every feed for 15 mins, hand expressing, pumping but nothing is working out. Please help 🙏🏻