If she likes hamburger, combine it with the rice. Add the hamburger to some of her kibble. Maybe a canned dog food will trigger the same response - try some of the chunky kinds, as well as the kinds that are 'pasty'
She's still pretty young and again, has been through quite a bit. Going off their food isn't unusual.
Since she's following you around, it seems like she's decided you're the alpha dog, her pack leader.
I think you're doing a very good job with her and are an excellent 'parent' already.
Let me know how it goes ok? Really!
(What's her name?)
Many have forgotten this truth, but you must not forget it.
You remain responsible, forever, for what you have tamed.