Losing weight to fit into a dress

RANT:

my dad and stepmom got married at the very very beginning of covid. because of that, we had a limit of 10 people so hardly anybody was there. my stepmom decided she wanted to take pictures at the end of this month with everybody in their wedding clothes. however, i have gained enough weight that my bridesmaid dress no longer fits. i went through a major depressive episode last summer and fall and with school (i just finished my first year in college) and working, i haven’t even had the time to exercise or anything. she gave me 5 weeks to lose the weight to fit into my dress. i also have body dysmorphia and she and my dad have made fun of my weight and body shape before. and on top of that, my little stepsister has a really fast metabolism and still fits into her dress and continues to make comments about how i need to lose weight because i don’t fit into my dress. i have told her that making those kinds of comment is rude but my stepmom says she just trying to be encouraging. is it just me, or is that fucked up? to make someone lose weight just to look good for her picture? oh and she doesn’t even fit into her own wedding dress btw. she yelled at me in front of my bf because i put a little bit of parmesan cheese on my broccoli and i just tried to grab a cupcake becauze i’ve been eating really good and she snapped at me again. i feel like i’m going to start pulling my hair out. while i do understand that i can afford to lose the weight, doing it just because of somebody else’s pressure isn’t healthy.