I think you must be a very kind person to find anything sympathetic in Mrs Norris, Billi! I have to say I found her totally unpleasant: bullying and unkind to Fanny, encouraging the vanity of the Bertram girls, and forever justifying anything and everything she did. See for a wonderful example her telling Sir Thomas about all her self-sacrificing behaviour when he protested to her about allowing the play to be rehearsed - it's masterly!
Of course anyone who needs to justify themselves as much as she did actually does have feelings of inferiority, but she's so unpleasant I find it impossible to feel sorry for her. I think she and Maria deserved each other.