Is it normal i feel fat?

My friend is a plus sized model and has been for about 6 months now. I just read an article of another plus sized model and when I look up their weights/heights, I get sick to my stomach and feel obese.

My friend isn't a runway model because she didn't want to go that route and she's not tall enough anyway but she does magazine spreads and catalogs. She's considered a plus size at 5'9 and 115 pounds. I've seen her in a bikini and she has no stomach, I can see visible ribs, I see her spine without her even moving and her body is just very skinny. She says her BMI is 17 so she never understands why she's plus sized as she's considered underweight but she goes with it. I know she's a size x-small in all clothes because we sometimes go shopping together and she gets a size 0 in jeans.

When I hear she's a plus size at 115 pounds size small and a BMI of 17, I assume I'm fat.

Plus sized means big to me so I know I don't want to be the fat friend. I am 5'4 and 128 which means I am a lot fatter than her because my bmi is 22 so it means I should lose about 35-40 pounds to be her size. This means I should weigh no more than 99 pounds but I feel it'll take a lot to lose so much weight. I want to get to 99 pounds or 90 pounds so I can be thinner than her because I really don't want to be next to someone who is plus sized and actually have a bmi MUCH larger than her. I must be morbidly obese or something if she's a plus size model at that size already. I want to see her work someday but no way would I go there if I'm a whale.

is it normal I feel so fat? I'm a freaking size 6 in pants.