Help! Night feeds

You should use all the breastmilk/direct latch and when it is not enough then top up with formula milk. For NB they dont drink much, 20-30 ml is enough but has to be demand. Example every 3 hrs, if you think breastmilk via bottle is wasteful, then try direct latch. I did this for both my kids, direct latch, with BM and last will be FM. Thank God they are on demand always for every milk consumption. But if you see only little consumption of BM via bottle then try other method, as mentioned direct latch. Slowly, it takes trial and error.

you can keep the milk to bathe them. my LO used to left 20-30 also. anyway, maybe try to reduce the amount as what they drink if after you reduce they still left 20-30 then could be the flow too slow and they tired to suck ( if you using extra slow teat)

how much do u feed per session? if you feed about 60ml but bb only drinks 30ml, then why not make 60ml but feed 30ml, then 10ml at a time. if bb only drinks 30ml then you only waste 10ml. Rest of the bm put back in fridge - can be used for next feed.