Really nice mare :)
Her back is slightly long, and her hinds are a little posty, hocks are a bit tall for a cutting horse. But she has a nice hindquarter, and from what I can tell, a good shoulder. She's balanced except for that slightly long back.
Not sure about QH's, but other breeds I've had matured late. So I don't know if you could expect her front to catch up to the rear or not. It's more common for QH's to be downhill.
"There are two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle." -- Albert Einstein