congrats on baby Olivia sounds like she's doing great and a good weight. I would not get too hung up on oz/time between feeds etc she'll let you know when she's hungry. Early babies really need their sleep as when they do all there growing so if she falls asleep mid feed thats ok. I was worried about only taking small feeds too, think my LO came home on about 2oz and I got myself all worked up is he/isnt he getting enough, as long as Olivia steadily gains weight she will gradually increase her milk intake (Matthew now takes 7oz 4 times a day - he dropped night feeds etc at about 4 months on his own).
If she seems more unsettled and grumpy right after a feed, wakes alot sooner between feeds or looking for milk earlier than her routine offer her another oz she may only take the extra 1 feed a day but she will build on it slowly.
Any excess milk I de-cant into a sterile bottle and store in fridge and goes toward the next feed, any excess I would disgard after 24 hours tho - at this stage im sure your not concerned about wastage tho.
How is Olivia and yourself getting on otherwise? You'll need to get a pic up when you have time us girls love cooing over our wee premmie miracles x