Poor student needs healthier microwave food

I think I maybe know what one of my biggest problems is. Or rather, I  feel like I can admit that I worry about my grades in university way too much and it's probably making me sick. I've always tormented myself over my school work, except for that little laissez-faire two years of truancy in high school. And that still bothers me for some reason.
I remember being in junior high and seeing a B for my social studies grade, and crying. Of course, now I'm sure everybody thought I crazy. I'm always forgetting to eat, and had a horrible realization about how visible my bone structure is getting. I felt a little sick when I was looking at my hands and could delineate the shapes.
I just need to relax and not worry so much, right?
It's not easy to change a way of thinking and behaving unfortunately. I have a terrible dislike and fear of appearing stupid, despite what some people might think. Being a very shy person doesn't make this any easier. I don't speak very much when I'm at school because I just can't handle looking foolish in front of people. I don't want to be thought of as "idiot girl" or something like that. This is a weird thing to randomly start thinking about late at night. But I really need to change my way of thinking and just cheer up. I can't continue my terrible diet and barely sleeping and worrying all the time about nothing.
I think I'll go to bed for real now.
Huh, my poor student life will improve if my mindset does. I hope!