I also am feeding Wellness. I’m using Small Breed Core and Small Breed Simple. The kibble is small size. I have one Cavalier that can’t eat larger sized. They also have Toy Breed, which may be even smaller sized, but I don’t believe it’s grain free if that’s desired. I also like Fromm 4Star. Very tasty (at least to the dogs, lol) and small sized. Annamaet is on the small size and they do have a small breed formula (non grain free) now. I always top their kibble with canned food to add variety and more moisture. I usually use Wellness Stews, Simply Nourish, Weruva, Fromm 4Star and also Vital Roasted Meals by Fresh Pet. Sometimes they just get a meal of Vital. I’ve never fed Science Diet and probably never will, but if it is truly all your little dog will eat then go ahead and feed it. Ultimately it’s your decision and your dog and we all have to do what we think is best for them.
