Samuel, I feel like your post would be better fit in current events and debates. There's already an open thread about this.
To the
OP, I'm sorry you don't feel comfortable using the bathroom in public places or at school. I am a cis female, but I was never comfortable using the public bathroom when I was in school. The nurse's office probably has single bathrooms that no one would see you use. If someone were to ask you could always say you didn't feel well or you could tell them you needed something else from the nurse and decided to go while you were there. If there's a section of the school with a bathroom no one really uses you could try to use that one. If you need to go in school, you could always wait until you're in class to ask if you can go so there's less chance of others being in there. You could talk to your teachers and explain why you wait until you're in class. As for public bathrooms, I feel like most people don't pay attention to who else is in the bathroom. I'm not sure how it is where you are, though. If people say anything, I would ignore it. I know it can be hard, but just remember that the problem is them. Not you.
I wish you the best.