I don't know why

I just needed to vent somewhere because i have the feeling no one listens anyways, I'm transgender but still closeted and i usually change on the toilet of the girls changing room for P.E. i don't know why they think it's funny to just open the door and look while I'm changing, i mean i locked it, yes, but they used a coin to open the lock and I don't feel safe changing now cause at any point they could just open the goddamn door and look at me, i don't know why it's so wrong to change there, i mean i have to change too, and if anyone has like suggestions what i should do, please tell me I'm out of ideas.