i think its normal to have their appetite to fluctuate, as it happens with us, it depends on many factors like age, level of activity, season change, heat, etc. So, as long as she is eating enough and acting normal in any other way i wouldn't worry.
My pulga has some days when she is like starving, she just inhales food and then is all they stealing pieces of kibble and sniffing the floor to see if she finds something, then some other days she barely eats all her food and has more interest on playing or other activities. Also maybe your girl is becoming an adult, did she have her heat? They do change their puppy/adolescent eating habits once they become adults
Keep on eye on her and don't get too paranoid (i know i do), am sure she's fine
