Any insight into sudden loss of appetite in my 6-month old?

I have been back to work for 3 months. My daughter eats 6 times/day. Once in the morning (6 am) before I leave for work, three bottles with the grandparents during the day and then twice in the evening (5 pm & 8 pm) before bed. She sleeps from 9 pm to 6 am.

Her three bottles with the grandparents used to total 12 - 14 oz; within the last week - we're lucky if she drinks 10.

Is she just getting more efficient with 3x/day that she nurses so she needs less during the day? Other ideas?

At her 6-month checkup (2 weeks ago) - her weight looked good.