I'm not sure what to tell you as i am having some problems with my son (he moved back in Too long to go in to Pm me if really intrested) But is this the neice who was raised by the brother who died? Didn't you say she had problems them? You are fighting the way she was raised, and you need to not apoligise but have a long Patient talk about sorry but life has changed these are my rules and if you can't live with in them find another place. Then actually make a chart of the day and what is expected. I know it sounds like your treating as a child but seems to me she is a little slow in her development and may need a structred routine. I know thats my sons problem. we have started back to it andhe is getting better. Maybe get her in to a socail setting (church group or hobby club ) of something she likes just any thing to get her moving and having a sense of self worth. Bet she blooms if she does.
I know you'll hate this next part it is hard for me too, but she was raised different and doesn't share your goal setting skills , hold your self in check and count to ten until she get's it on how your house works. Sending you huge hugs I'm there right now too.