My MIL did the same thing. Kept telling me to stop BF and give FM. When bb 4 months old, kept insisting that I start her on solids. They come from a generation where breastfeeding wasn't encouraged and babies ate lots of porridge.
I used to do what you're doing - baby drank very little milk during the day, but latched on as soon as I got home and BF every hour till bedtime (I suspect that's how baby filled up for bed. hehe). Also gave nite feeds.
So long as your bb is still within the normal weight and height range and hasn't suddenly lost significant weight (check with PD/doc), it's fine if she consumes less for a while. It could be a transition period cos you just went back to work. Keep monitoring her growth/progress.
Store your bottles of BM in an airtight container, so that the fumes from other food (especially raw meat) in the fridge will not go into the milk. Inform your bb's caregivers that thawed/warmed BM should be consumed within 1 hr. Throw away the balance after 1 hr. Thaw frozen milk in the fridge before the estimated feeding time. When it's time to feed, warm the thawed milk in warm (not hot/boiling) water.
You could just open a bottle of BM to check. I tasted and sniffed my own BM to check taste/smell. I figured that whatever I expect my bb to put in her mouth, I must be prepared to put in my own.
If the BM tastes/smells normal, most likely your bb is just rejecting the bottle. Try different bottles. Try feeding baby when she's half asleep. My bb was like that - only drank when half asleep. Another mommy on this thread also shared the same thing
I understand what you're going through cos it sounds very similar to my own experience. Take comfort in the fact that other babies have gone through the same thing and overcome the rejection phase