Formula feeding question

Jeanette • Married the love of my life 4/18/15 & got BFP 4 days after missed period mid morning 10/7/15 expecting 2nd child❤️👶🏻🎀
...is 3oz too much to feed a 1 week old @ night? I breastfeed during the day but started formula at night b/c breastmilk wasn't filling the baby up and she was waking up quite often.