How about just pumping and saving?
I did that for 3 years over 2 kids. never used formulas- just for
tests, that turned out with bad reactions.

You can pump a lot after your milk comes in and the first few months.
Especially focus on the overnight wakings, or early morning, when the
baby goes back to sleep. The more you pump (and drink) the more you
make. Use a bag marked with calibrations. Then use a laundry marker
(non- water soluble) and write the date and amount on the outside of
the bag. use a twistie wire to close the bag. Put it in a low-
temperature freezer for storage for a few months. A low temp freezer
is one that does not defrost automatically, and is at about -10C.  A
frost- free freezer spoiled my milk within a week. I also put the
bags in a separate box to contain them, and wrote on a piece of paper
the date and what went in to the box (eg 7/7 4 oz- or use mL). When
take some out, scratch out the corresponding numbers. defrost under
warm water. Microwave heating spoils it w/in seconds. This is my
experience, yours may vary.

Help is available from la leche league (has website).

I also contacted a milk bank- they would be thrilled with donations
of human milk that was allergen- free. Needs to be from mom before
baby turns 1 yr old. I'd have to look up that website, too. Maybe
Australia has something similar.
.