night feeds

So my LO and I are really struggling with night time feeds, well all feeds but nights are extremely difficult. I have been pumping and hubby suggested that I give a bottle at night so we can all get some sleep. We are also having to supplement 1 oz formula due to wt loss ( more than normal). Anyway I am heartbroken by his suggestion however after tears on both our parts (baby and me), it may not be a bad idea for nights. My question is how much breast milk should I prepare? LO is 9 days old. Thanks!!