Oh, sorry for confusing. I didn't realize the first けど, so my words was for the last one.
You are correct. The subject of 思っていない is 彼女 in this case. 彼女にしてもあなたの考えがすべて間違っているとは思っていない refers to "she doesn't view all your ideas as mistakes" part, and "I definitely think" is for はず.
(I definitely think she doesn't view all your ideas as mistakes. = I definitely don't think she views all your ideas as mistakes.)