I'm having the same problem. My baby girl will eat, but not enough!
She's tiny enough as it is and has now lost 4oz, putting her under 2lbs.
I got some great tips in this thread, maybe some will work for you? I'm still trying them.
http://www.yorkietalk.com/forums/showthread.php?t=78182
Good luck!!
Chloe loves the Gerber meat sticks (as suggested by another YT member), btw!!!