Wow, congrats on the puppies. I know it is very stressful. Between the smell and the blood, timing (my mama went started whelping at 2 am
) and then , all of a sudden, it just doesn't seem to be going right. The main thing is to stay calm. I know it's hard, but your girl can sense that immediately and that makes her nervous... I'm assuming this her first as well?
If the puppy doesn't latch, try sticking your finger on the puppy's mouth to see if they will try to latch on. You may have to bottle feed the pup, too. Either way, I would call in your vet and see if a vet tech or someone with whelping experience can come help. Those are my suggestions.