Yeah. I don't think Diana is doubting herself. She is quite possibly asking herself if she managed to navigate and improve Man's World to the best of her ability, but those are entirely fair questions to ask after the various poor runs she has had lately.
Better writing could have made that clearer, but then it'd have run the risk of being too preachy. But mainly I think Nord's poor way of depicting Diana's face and posture contributes to presenting her as insecure and doubting herself.
«Speaking generally, it is because of the desire of the tragic poets for the marvellous that so varied and inconsistent an account of Medea has been given out» (Diodorus Siculus, The Library of History [4.56.1])