The premise is this (fat) girl has had 25 ish Crushes, but zero rejections because she never puts herself out there, because she has a lot of emotional baggage from how she's treated due to her weight. I can certainly empathize on a level with that.

So naturally she decides that a rejection will inoculate her, and rejection will get her a boyfriend, hijinks ensue.

I want you to rest assured that while the protagonist seems to be heterosexual (at least she never showed interest in girls in the book) there's plenty of queer women and girls in the book.