Do you think my mom is criticizing me too much?

She doesn't want you to eat junk is all. She didn't say you were fat, just that you could become that way if you have poor eating habits. Its true that no matter how thin you are now, eating junk will make you fat eventually. Just because you can eat junk and not get fat doesn't mean it isn't doing you any harm. Its not like only fat people need to eat vegetables.