Mom tells me I'm fat

I apologize if you've already seen this but I'm posting to a few different groups for more answers.... Ever since I went on birth control I've gained a lot of weight. Obviously I know I've gained weight and I'm very insecure about it. My mom has lost a lot of weight and therefore makes subtle remarks about how I'm getting really fat. She's a little bit bigger than me but for the most part around the same weight range. Just because she has just recently lost a lot of weight she uses bringing me down to make herself feel good. For example she has a thing now for asking me to borrow my clothes. It fucking annoys me because yes even though you may be able to physically get my pants onto your body doesn't mean it FITS. She takes my clothes without asking and they're tight on her but she thinks just because it's physically on that it fits and looks good. This pisses me the fuck off because as a result my clothes get stretched out and I just don't like her thinking my closet is hers too now. It fucking aggravates me because she knows I've struggled with my weight my whole life and as a woman she should know fat jokes make someone feel like shit. My mom is very insensitive and she doesn't get it when I try to explain how I feel. She says I can't take a joke but she doesn't get that it HURTS. It's so annoying and I'm going nuts! Now my little 7 year old brother makes comments on my weight and he learns it from her! The other day he told me "you're never going to have a boyfriend because you're fat, you need to go on a diet" LIKE HES 7 YEARS OLD SAYING THIS WTF?! I'll correct him and say it's not nice and he'll say "I'm just kidding" I say "yeah, but that doesn't make it right" and he laughs..... it breaks my heart, it really does. I'm so fucking insecure about my weight and I'm currently working on it but the birth control doesn't help. I'm thinking about getting it removed, that's how desperate I am to feel happy in my own skin.... I'm 5 ft 2 in and 175 lbs. I cry when I shop for clothes.... I feel like shit when my boyfriend looks at me... I feel like shit every day. I'm constantly insecure about how I look in regular ass clothes. Even if its 95 degrees outside I'll wear a sweater because I feel exposed if I'm wearing a t-shirt. It's sickening. It really does control my life.... it affects a lot of decisions I make. I won't go to prom if I don't lose 50 lbs.