Honestly as hard as it is to do, try keeping the treats away from her completely. Those bully sticks, rawhide chews, ( < they swell up in tummy ) any goodies, are filling. If her health is fine, then when she gets hungry, she will eat. Being tiny the treats are yummier and might be why she is not eating completely.
I’ve had rescue dogs for 50 years and have learned quite a bit and still learning. I had to cut out dog treats because my dog was putting on weight and tore her cruciate. $4,000 for ACL surgery. Her weight was causing damage and she went from 60# to 42#s and felt a lot healthier.
Just a thought, but try filling a KONG up with low fat yogurt, oatmeal, some organic honey, organic peanut butter and mix in some kibble. Freeze overnight, put a towel on doggie bed and let her go at it. My dogs loved them. Having 3 dogs at once I used to make up about 5 days worth and freeze them. You can slowly add more and more kibble and less yogurt. Just work out the consistancy so the food stays in.