I'm insecure about everything I do at school (13M)

I'm in 8th grade now, and it's been like this ever since 5th grade. I feel like if I walk wrong, if I talk wrong, or even if I sit down wrong, I'll be seen as some weirdo by students, and it's not some sort of guess, either.

I have none of my friends in any of my classes, so I'm always quiet. My voice sounds dorky (it sounds like a lower-pitched SpongeBob). I honestly feel disgusted with myself in a way. I just want to put this feeling to an end. This is the one thing I hate about school.

I just want to stop giving any shits about the kids at my school and actually enjoy my academic experience. It's hard to do.