Urgent help needed , air sac seems to be too large

[yuaan]

I have places 12 eggs in my mini Eco brinsea incubator. 3x silkies and 9x sable poot. It's has been just over 82 hours and I know that it was too early to candle the eggs but I am curious what is going inside the eggs .
To my surprise the 1,2,3,5,6,8,9,10,11, are fertile as I could see the little heart beating and web of blood veins attached however the egg number 4 and 12 are empty no sign of heart . The number 7 look rather early death as I could see bit of red veins like broken and scattered inside the eggs and there is no heart to be found .
Does it mean that number 7 is early death ?
Second question: the air sac if I compare to the day one and after 3 days have gone big in size . Is it fine or there is something I should do.
My incubator is constant on 37.5 tem and 45 to 47 humidity . Are my eggs developing fast as its just been about 3 days of incubation and theory the 1 day does not count anyway but still if it is day 2 then is it not too early that the chicks are developing too fast .
Here is one of the egg pic , hope you guys can see what I mean

 

[Kelsie2290]

https://www.backyardchickens.com/a/hatching-eggs-101
Have you seen this from the Learning Center on byc?
In general, if your air cells are too large for their age you are going to want to up your humidity. You might be better off to weigh the eggs and keep track of the weight if you can't judge the size by eye. You have until they hatch to have the size of the air cell adjusted, so since it is still really early you don't need to panic if they are a little large or small right now.
With the early development, mine always seem kind of variable the first few days, then the normal healthy eggs seem to all pretty much catch up to each other, if there is a really small one later, it usually has a problem and won't make it.
The #7 does sound like it died, but I usually wait until day 7-10 before culling any, unless they are rotten/leaking/smell.