How much will I need to express?

DP and I are attendants in a wedding in 3 weeks time. My parents will have DD for the day/night (the first time I have been away from her) and we are planning on feeding her expressed breast milk during this time.
How often should I express over the next few weeks? She is still feeding every 4 hours approx.
We tried her on a bottle a few days ago and she took to it really well but thinking of switching bottles as she had a lot of tummy trouble the next night (not sure if related or not)
Any advice would be greatly appreciated!

If she's eating every 4 hours, you'll need what, 6 feeds? I pump for a freezer supply, I've found it works best for me to pump once a day. I pump after DD's first feed in the morning...first I'll do the boob she fed off and then the other one. I usually get about 120ml, so about one bottle or feed.

Don't be surprised if you can't pump as much as PZ at first, or at all, pumping works differently for different women. I used to get about 60ml (on a good day). I also found morning the best time to pump.

You will also have to think about how you will pump while you are away from bub, and whether you want to keep the milk (how to store it).

It is also probably better to freeze in smaller (60-80 ml) lots. That way bub can have 1 lot for a snack or 2 for a bigger feed, and less gets wasted .

Here is some good info on caring for the breastfed baby, great for grandparents or other carers who might be looking after them.

Australian Breastfeeding Association - A Caregivers Guide to the Breastfed Baby

On average a BF baby takes about 700-800 mls a day with a range from about 650-900mls. My LO usually takes about 800mls. You just divide that by the number of feeds a day to work out how much you will need.