Joysome,
For whatever it's worth, parents, like everyone, fall into the trap of wanting things to stay the same. I know its hard for me to imagine my little girls all grown up. Your mother, perhaps, just can't see what the future would be like with you in a new paradigm, and it scares her. What she might be coping with, is the fact that the most fundamental change has already happend: you aren't a JW, and are free to make your own decisions. That is light years away from the JW mental slavery she is used to. So it will take time for her to understand. Meantime, you get to live your life.
Good luck with getting your sugery approved. I hope it goes well. Someone close to me had that surgury where they reduce the stomach to about the size of an egg. It has worked well for her, although, of course, she has had to relearn all eating habits.