Need help regarding breastfeed

My baby is 6 days old, I’m a first time mom. I am unable to breastfeed my baby but I’m am willing to. I have few issues if anyone could help me

1) breast size is big, and nipples face down.. I’m unable latch my baby

2)my nipples aren’t erecting enough, and my baby’s mouth is small

3) my breast is stuffed with milk but the milk isn’t flowing easily out of nipples, because of which my baby has to apply too much of force.. which he can’t.. he tried then cried a lot.. i try to stick him but now he stopped trying..

I’m expressing my milk and feeding him.. but it’s extremely painful because it’s not flowing properly through nipples.