Hi,
Your little daughter probably needs time to adjust to a new caregiver. Did she nap better when you were with her?
First of all, you know better how to read her tired signs and put her down for a nap when she is ready. A new nanny, regardless of how caring she might be, will have to learn to see subtle clues your baby gives her to understand when she is tired, hungry or bored. It will probably take some time, unless you have a set schedule for her to follow. Even in this case, your baby senses a new person around her and may act differently than she used to. It is amazing how much our little ones understand.
Each baby has a different apetite but your dd taking 3 bottles of 3.5 oz in this time slot sounds quite normal. You didn't tell us how many bottles or feeds per 24 hours she usually has. If before your return to work she was at the breast every 2 hours and now she seems not to be taking much, it may be due to a stress. After all, her mom is gone, and a new person takes care of her, this is a huge event for your little one, she may not be napping well also because of this change. Now, she has one longer nap, she was exhausted from being awake for so long, that's normal.
As for how much your baby should be drinking in a day here is an info from kellymom.com:
The research tells us that exclusively breastfed babies take in an average of 25 oz (750 mL) per day between the ages of 1 month and 6 months. Different babies take in different amounts of milk; a typical range of milk intakes is 19-30 oz per day (570-900 mL per day).
I hope your daughter will adjust soon to this new arrangement
.