I had my taste buds change about 4 days ago (I'm 2 weeks post op). It's awful!! I can't taste sweet spices at the moment, like cinnamon and nutmeg. Perfect time of year to not be able to taste those things! LOL Also a number of savory things don't taste right anymore... I hear this taste change happens a lot in the 1st year.
As for your family, you are going to have to set some firm boundaries there. I know it is hard to do with family, but if you don't set them now it'll only get worse. Just tell her you've had enough and you'll return to it later, then put your plate away... Tell her you get labwork to ensure you are getting enough nutrients, she doesn't need to worry. Your body is different now and your food needs are different. And that what you need most from her is SUPPORT in this new way of life, not encouragement to overeat. Parents have a hard time seeing their children as responsible adults who can care for their own bodies and lives. Sometimes we need to (kindly) remind them we've got this.