Could you try offering from a syringe? I mean, it's not the most conventional method and sure not for such a large amount but it might be worth a try.
I think the taste of breastmilk is also different to them and the temperature as well - like you say nothing is quite as good as 'on tap'.
I think she is probably a little bit young to rely on only food for the day? My DD is about 6 weeks younger and there's no way she would go without milk for a day!
I guess maybe defrost a little less for a little bit longer?? See how she takes it after a few more days?