There’s no need to feel guilty. My baby has been drinking frozen milk since a few weeks after she was born, as she was hospitalised for a few days due to jaundice and that’s when I started to have more breastmilk and subsequently she wasn’t drinking well, thus the accumulation of milk. It is fine to freeze the milk away but remember once thawed for 48hrs it must be thrown away. She’s growing fine and strong. Also never re-feeeze the milk once it’s thawed. Anyway, there are papers stating that frozen milk is fine, though some nutrients will degrade especially those that are sensitive light. And of course the longer you keep it frozen, the more nutrients will be gone. So one word of advice, first in first out.