I encountered the same type of situation today, and I let it get me really really bummed..im so down, I hate emotions..
A girl in my class used female pronouns towards me, and stupid me was surprised. I have such a high voice and im so short, and all these ppl are like 17+.. I can't believe I expected to at least pass as a kid, a little boy in there.
I didn't say anything, I just put my head down.