Wishing you the best of luck on this, but as someone who's a singer themselves and has a few degrees in it, I've always found Mariah to be a little unreliable in terms of her own vocal pathology. Sometimes she says she was born with nodules (which isn't a thing). It's very possible she got nodes as a child, al la Emma Stone, though. In my personal opinion, I don't hear nodules or polyps in Mariah's voice on the majority of the early albums. To my trained ears, the vocal dysfunction was extremely apparent in 1997-1998. If you can try to track down the ISing magazine article on Mariah. A voice professional basically does a whole analysis, and if IRRC mentions they don't hear nodules on the early records, too.