Her neck is on the short side, set on low and is under muscled. Her back does have a bit of an upward arc to it, but I don't know if there is anything that qualifies as a roach. The pelvis is big and has a good angle to it. It is her best featurem, in my opinion. Her hind leg is a bit posty, with the stifle angle and hock angle a bit more open than is optimal. Rear pasterns are also upright.
Front leg is a bit dainty of bone a bit hard to see knees (dark picture) but look ok. Her shoulder is somewhat upright. Her ribs look well sprung and heart depth looks prettty good.
She just looks a bit like her front half of her body just isn't nearly as sturdy as the rear. But I can't see anything "wrong" with her. If you love her, and she loves to go out and ride with you, then that's all that matters.
As for the pedigree, I know nothing about QH breeding, so won't even try to make any comment there.