My girl will be 9 months next week. I am a full time working and breastfeeding mom, but she is demanding more pumped breastmilk than what I can provide the babysitter. So, we tried to use frozen milk that I have stored, and/or formula. Problem? She rejects both. We've tried different times of day, brands of formula, etc. I think the problem with the thawed milk is the taste--it smells soapy and/or rancid. The formula also smells very different. She has never had a problem taking fresh pumped breastmilk from the bottle. Any tips?