J.R.
Have you tried a cup, spoon or medicine dropper? It may be slower...but it may just do the trick.
For what it's worth...I worked & pumped with all 4 of my kids. And it was quite "normal" for all of them to take 8 oz or less from bottles the whole time I was gone (up to 10 hrs at a stretch), as they waited for me to get home so they could get the milk "fresh from the tap." I learned to cope...that is a lot of why we ended up co-sleeping.