No way of knowing, really, as Appys are a color breed and so typically don't have a specific, relatively recognizable conformation.
With her being so thin, it is also hard to say but to me she looks like a Quarter Horse or possibly Appendix.
Also, from my past experience in owning a "pink papered" appaloosa, they typically display at least a few appy traits if no spotting like the mottled skin, white sclera or striped hooves.
There wouldn't be any way to tell unless you had her papers. Like lilruffian said, appaloosas do not have one set conformation type. Their stud books have been open to cross breeding so they vary from old foundation type to modern QH type to TB type. There are even some that look Arab-like or Morgan-like. Your horse looks appendix, and could very well be appendix, but pink paper appaloosas could look appendix in appearance too. Pink paper appaloosas do not need to show any traits though. They can, but many do not. My own appaloosa gelding is registered and papered, out of two coloured parents but he has ZERO appaloosa traits. He has no white sclera, no striped hooves, no mottled skin. He is just bay. So, unfortunately, there is no way to prove your horse is or isn't a pink papered appaloosa without a pedigree. Your horse does look a lot like mine. They have similar hind quarters and they both have a long back, though this doesn't really mean anything. Congrats on your new horse though! She is a cutie!
She is uphill built, and so thin its hard to tell. She could be a warmblood where they do breed for the uphill and she is sway backed which can happen in any breed.
I don't see quarter horse / appendix quarter .