I'm a small girl, but I'm not attracted to a guy who is tiny like me. Most of my friends aren't attracted to small/really slim guys either. We like big guys, guys with some meat on them. I don't like steroid bodybuilders, but I like a guy with a healthy proportion of muscle and fat, not ripped up, but not lardy.
Most of my male friends have admitted that they're trying to lose weight, and none of them are fat at all. If anything most of them need to gain weight. Why do guys think that girls want to be with ultra skinny guys? Most of us don't find guys who wear smaller jeans than us to be attractive. We want men with size who seem masculine and strong. A guy doesn't have to be really tall or anything, but he can't be so tiny he can wear my clothes.
The problem is that a lot of guys are clueless about what girls really want. They actually apply their standards for what's attractive in girls and believe that girls find the same features attractive in guys. That's why there are so many guys who suck up to girls trying to be nice. It's also why guys try so hard to get skinny, because they think that since they're attracted to skinny girls, girls must be attracted to skinny guys. It's a false equivalency, and it's why so many guys can't get dates.
Skinny guy here. I (and many others) tend to be attracted to body types I admire/wish I had. I'm attracted to athletic, flat out muscular women because, in a way, they have the body that I want. My girlfriend is the same. She is tall and a little overweight. She likes skinny guys because that is the type of body she wants to have for herself. Not always that simple, but I have seen it a lot. You seem to have it too where you are small, but are attracted to bigger guys.
Also, I think generally men are getting more feminised by society. Feminine men are being encouraged, women have more power in the world. It's no surprise that fewer men feel the need to be these big muscle men.
Because most guys today are feminized little bitches who don't understand girls. Guys see pictures in fashion media/advertising, most of which is controlled by gay men, and they believe that thinness is what women prefer.
I don't know where you come to the conclusion that guys think girls like skinny guys. Infact, it's the opposite. We guys know that girls hate scrawny guys. They're losing weight in order to build muscle
My entire life every time I said something about getting bigger girls told me not too. They even yelled it sometimes like I was about to squish a puppy or something. I'm 5'10 and I fluctuate between 135-145. Up until last year I was 132 to 137. And I'm by comparison thinner than most my friends. I've only ever heard one girl say I was too thin, it wasn't to my face, and she was also taller than me. Her friends immediately disagreed. All most all of the pressure to get bigger for me has come from guys In thier teenage years and 20s. After 30 almost all of them give about staying healthy and taking care of your body. The only guy older than 30 that commented on me building muscle was my ex's ex-stepdad. Who was single and a little bitter. I think where you grow up has a huge influence on what type of body shape you think is preferred. I remember a study a while back about how women who grew up in lower income areas no matter what their current income is tend to slightly prefer larger men. I didn't look much further into it so i don't know how valid it is but it's still interesting to think about.