Just like people, some QH are short and squatty and some are taller and leaner. Some people breed for the short and squatty and some breed for the taller and leaner.
My QH is short and squatty. My barn owner's QH does not have TB in her either, but is taller and leaner. Different types of the same breed.
As the others have said if there is no x and no TB within 4 generations, then she's not an Appendix.
"When you're young and you fall off a horse, you may break something. When you're my age, you splatter." -- Roy Rogers