how to keep breast milk

[forevermore]

i have a 2 week old and missed a feed so expressed and got 3oz. I have a few questions:

how long can this keep in the bottle refridgerated.?

how could i freeze this...what container?

is this enough to supplement a direct breast feed? or is 3oz too little? i know 3 oz of formula is okay fo this age, but how much EBM should be given in one go?

It should keep in the fridge for 24hrs. Not sure what is best to freeze it in. And I think 3oz of bm is equivalent to 3oz of formula.
HTH.

8 days in the main body of the fridge, six months in a proper freezer (not an icebox).

Lansinoh do bags which are great.

Avent also do bags, which are great for storage, but fiddly when defrosted. I transferred to bottle instead of using their disposable system. You can freeze in any container, but remember it's useful to know how much and you need to date it or remember when it was expressed so it doesn't go out of date. Bags take up less space in the freezer and after a while i had a bottom drawer full of it!! so was glad to use bags.
I was under the impression it was 24 hours in the fridge and 3months in freezer certainly it worked for us. My dd had ebm from 4months when i returned to work, fed by Nanny and bf when i wasn't working from me. It worked well, and she progressed to bm on her cereal at about 6months. i used to make up small and large bags of milk, and depending what time she would want feeding and the likelihood of her drinking it depended what size i defrosted, so as not to waste too much.
You probably won't need to supplement a direct bf, as baby can feed from you, and top up if they need, so you don't need to keep track of amounts in the same way, although i would have thought that it's similar amounts but formula is heavier on the stomach.
Try giving baby 3 oz then offer breast and see if they want anymore, if not 3oz is fine.

Good Luck