Rollie: How old is your kitty?
As a vet, I have to agree with the need for bloodwork and urinalysis. She could possibly have a little kidney problem going on -- it often can cause finicky eating as a first clinical sign. Hyperthyroid often starts as "overeating, yet losing weight"... later it can lead to not eating as well, but not at first.

Either way, with the history of vomiting, and weight loss, I'd highly recommend bloodwork. At least you will have a basis on which to rule out other problems, and concentrate on whatever else may be going on. And an x-ray can SOMETIMES be very useful, and other times not so much. Unfortunately, you don't know if they help until you've taken a look at them. So keep this open if no other answers show up.

And obviously, if she is outside / hunter, have her stools checked for worms, and consider routine deworming for roundworms and tapeworms just to cover your bases.

I hope you come up with some answers soon and that she is feeling better. She is a sweet looking girl!
Jes