Heavy Girl

I don't know if I want to label this as bullying, but here goes.
I have never been the healthiest weight. I've always been on the heavy side. People are always telling me to not be insecure, but I know people look at me differently. It was always sort of subtle, two skinny girls would give each other a look if I said something remotely confident, or a boy would mumble something if I mentioned dating. I always felt there was an underlying tone of "I want you to think I want you to be confident, but I'm also disgusted by you. So you shouldn't be confident." Typical "the skinny man's burden  stuff.  Any other fatties will agree with me that no matter how much a skinny person says "you're beautiful just the way you are!" what they are really saying is "I don't think you're beautiful but maybe someone will someday! Be happy for that!"
People wave it off and and act like I'm over reacting because I'm insecure, but trust me, I know when I'm being judged. I guess this is the type of thing that is never actually considered bullying, and I had come to terms with that. I mean how do you report a "look" someone gave you? So to prove my point, here is one of the more obvious circumstances.
One day I was minding my own business chatting with my friend John. John and I were really good friends and he had recently come out to me which only made our friendship grow stronger. Since no one had any idea he was gay, they immediately assumed I had a crush on him (he was very attractive) and that I was following him around like a puppy. He started telling me how people were saying I was pathetic for trying so hard and how he would always defend me but it didn't seem to help. So anyway, we were in class and one of his guy friends comes up to us and says, very loudly "John are you going out with her?!" we both responded "no" and he said "good cause I was like," he looks me up and down, "ew."
And then he just walked away with a smirk on his face like he had done good. It was humiliating and no one but John showed any sympathy for me.
I know If I had reported that to any teacher they would have maybe given the guy a talking to which would have only made things worse.
I feel bad because I just sound like a whiny fat girl, but deep down I know that's just because people have told me all my life that I'm a whiny fat girl.