My son doesn't have any single obsessive interests, but I feel strongly that AS is the right diagnosis for him.
Honestly, though, what it boils down to for me is this: a diagnosis is only worth what it can do for you. If you feel you understand your daughter, have a sense of what she needs in the way of services and accommodations, and are able to access what she needs, then you stop looking. At least, until things change and new issues arise (as they always do, no matter much time you spend on this now). If you don't have that, you keep looking.
At this age the most important thing for your daughter is to get to be herself, developing and discovering on her own schedule, and the world responding to her instead of her having to conform to the world. If you've gotten enough from the professionals to meet that need, you can set aside the questions for a little while. In a few years everything will change, and while being prepared is good, the main focus right now - IMHO - is just letting her be who she is.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).