I agree with all the PP
You said you were expressing, could you try topping her up with EBM instead of formula? Also I would do what the LC suggested, pop her back in. Even if she falls asleep and is just comfort sucking she is still stimulating your breasts.
I am crossing my fingers for you and sending you loads of and leaky booby vibes!
But please, if you are driving yourself insane and not getting results, don't let your mental health suffer.