she doesn’t know yet, i think. When she said that in the beginning chapters it’s after everything happened. These chapters are explaining what happened before she found out she was misdiagnosed
She wasn't misdiagnosed. She really had an illness, something with tangled mana, I don't remember exactly. To cure it, it would take someone with at least the same level of mana as her and since she has a vast amount of mana it was practically impossible to cure her. Coincidentally Doha has a similar amount of mana and he noticed her condition and healed her in their sessions, only that he didn't mention it to Lariette. I don't remember why Doha kept quiet about it, maybe it was something trivial to him or he didn't want to worry her thinking she didn't know, I would have to re-read ;)
Wasn't she misdiagnosed...