First of all, and please don't take this the wrong way, but you NEED to STOP switching foods all the time. I know it's frustrating when they don't eat, but it sounds like she is eating, just not as much as you would like. Changing foods all is definitely not good for their systems. Pick one brand, purchase the kibble and canned and stick with it. If you want her to eat kibble, you can soak it in warm water for a bit to soften it up. Or there is nothing wrong with adding a bit of canned to the kibble 2x a day to entice her a bit more.
It sounds like she is fine and you are just worrying
I would get a bile acid test done on her when she's about 6 months old to rule out any liver problems. This should be done on all yorkies anyways.
Ryder was 20 ounces from eleven weeks old to fifteen weeks old. He is now a healthy "think heavy" three pounds (really 2.8 but we like to tease him
) at a year and a half.
Oh, and as an FYI- Nutrical can seriously supress the appetite if given too much/too frequently. Good luck!