Ohhhh, those days of "morning sickness" is enough to worry us sick!!
Starting at about 3 - 3 1/2 weeks until about mid 5th or beginning of the 6th week, my girls go through this same thing. No matter how many times I go through it, every single time I worry like crazy, try anything & everything to get them to eat, and yes, resort to force feeding them some just to get a little nourishment into them. Then that MAGIC day arrives when suddenly they begin eating again...........and eat, and eat, and eat!!! And every single time, the mom is fine, the puppies are fine, and all's well and end's well.
Good luck to you and Princess, hopefully her "magic" day has come or will very soon.