How can I find my QH's reg. information without having her papers?

AQHA are DNA'd when they are regd. Maybe you could send a hair sample in and see if they can match it. Your best bet is to call the AQHA and see what your options are. Other wise yes if she is branded, you could trace back to the stud. I have 2 regd QH, one is branded the other isn't.