She does, the review on 25 by experts has it at 3 octaves & 4 notes. It doesnt really matter tho many legends have limited range. Its how you use it and how people recieve it.
I have 3 too. Doesn't mean I sound good. You know, you have to be able to control your voice whilst maintaining a nice tone. Something Rihanna is yet to accomplish.
And by the way, Adele does actually have 3 octaves.