I.G.
My daughter is almost the same age and like that sometimes. I know EXACTLY on which days she will whine... it is those days where I think that I am too busy with other stuff to invest the time to give her one on one attention.
I am a full time working mom too! I understand the need for a second income to keep a roof over your head and have a good life for your family.
HOWEVER, I do not fool myself into thinking that the time she spends at daycare (and we have a truly excellent daycare center) is the best option for her. Yes, her teachers care and give her attention, but it is NOT the same as parenting. It is not the same as sharing that psychological and physical bond with your kids.
You mention that you have things to do at night, and so do I. Sometimes it's hard for me to let go of the laundry that needs to be folded and the dishes that need to be done. However my child did not choose for me to not be able to care for her as I should, she did not choose to spend 9 hours a day in daycare and NOTHING that I could possibly have to do should be more important to me than spending an hour cuddling, reading, talking to her, one on one, with my full attention on her.
Since it's the same time each night, try to break the circle by switching up your schedule... take her to the playground instead of going home, give her veggies for a snack and accept that she will eat less at dinner.
It's hard, I understand...but sometimes bending your expectations and rules and being happy is a LOT better than sticking to something that does not work.
Good luck!