If she makes a comment like that again just drop your jaw down on the floor and cry: "WHAT!!! I have been eating only lettuce for a week now and my scale said I dropped about 100 grams!!!!!! Are you sure ... when last did you have an eye test??"

Seriously, I would take her aside and ask her if she has a problem with you and explain that after putting on a WOPPING 3kg's, you are still a woman and very sensitive about weighty issues and would appreciate her not refering to your weight. Explain to her that even though she might think that you don't take it to heart, it goes straight for that soft bit in the middle. And tbh, I don't know why your mom does not say something to her. She is being rude. I agree with the girls that she is probably jealous of your petite figure, but that does not give her the right to be rude and sure as hell not by hurting your feelings to make her feel better.

And for gaining weight when pg - OF COURSE you must. SHE of all ppl should know that. Just keep going to the gym and take note of what you eat and then you will pick up the pg weigh NATURALLY and drop it just as naturally.

Good luck with the IVF. Hope all goes well and you are pg asap