I'm leaving my 9.5 month old with OH for a half day this week (first time we'll have been apart!) and I plan on leaving him some expressed milk for her afternoon feed. I've no idea how much I need to express though. We had a practice just before Christmas and I managed to express 3.5 oz in one session and she drank 2 of them. That doesn't seem very much though, so presumably I need to do a few sessions to leave a bit more; but how much?