starting w/#2 --- I don't know what makes you believe you are difficult? Not at all. I haven't seen any hostility-----hugs!!

#1-- you can tell your t at any time what is triggering you, but maybe her using the nickname affectionately can help "reclaim your name" and give it back the positive feelings that should go with it. If you let her keep calling you this, your grandma's bad behavior may be pushed to the background and your nickname can be "yours" again--hope this makes sense