I could never get much with expressing either, but its the stimulation that counts for you, the 20mls in a cup is fantastic for her if she's refusing to feed off you. I wouldn't try cows milk yet but thats because our family has issues with it, you could try 1/2 water & 1/2 cows milk to dilute it and see how she goes with it. I think if you could give her a cup rather than bottle its heaps easier in the long term as she wouldn't need to be weaned off the bottle as well.

Is she teething? Is she sick? Sometimes teething & sickness can cause them not to want to suck on anything & if thats the case a cup would be best for her anyway in the meantime.

I saw a LC for our breast refusal and its the best thing I've ever done.