How often does he feed? I'm sorry I can't remember how much I used to leave at that age, about 80ml a feed from memory?? I would also try and feed just before I went out. I didn't thaw too much as I figured if worst came to worst they could use the microwave to defrost it very carefully. I was more worried about wasting the ebm than microwaving a d and reducing it's immunity value. I think the website kellymom has a great guide and I used that to start with