Latching problems

I had to have an emergency c section and then baby went to NICU. He’s full term - 4 days old today and we just got released from the hospital. I’ve had to use a nipple shield to even have a chance of him latching on and this barely works. He’s basically been on formula and supplementing with my breast milk off and on. I’m pumping about 30-40 ml total in a 30 minute pumping session. Once I build up enough supply, I’ll probably start giving these to him through bottles (or family members will) but in the meantime, how can I possibly get him to latch with the nipple shield? I’m trying so hard and I just end up bawling my eyes out because I feel useless. Any tips?