Hi again,
By 8 months your DD is probably a very efficient eater, getting quite a lot of milk in 5 minutes per side. I know my DS was only doing single sided feeds for about 5 minutes at that age (any longer and it interupted his play time

He now is back into a more leisurely feeding routine but for that phase around 8 months he was managing fine with only short feeds. I think the key is that she is happy and content - I'm sure she would let you know if she was hungry.
Good luck on continued success during the nights!
Cheers
Jo