Changing Language in Classrooms

Asher
My challenge occurred while subbing for a 5th grade science class. I was asked by the permanent teacher to work with the kids on a cohesion lab for the 4th-6th grade classes. The day began well. I gave a short lecture on bonding and cohesion in water droplets and did a demonstration of the lab the kids would do. The kids were receptive and relatively well behaved (only a few kids needed to be prodded to not goof off). They completed their experiments, recorded their results in their lab notebooks, answered the assigned questions about the lab, and, when the bell rang, returned to their homerooms. I was feeling good about the execution of the lab and class management.
However, after lunch, I stood at the door of the science classroom waiting for the next class. It was a 5th grade class and the permanent teacher had told me that morning that the class was very well behaved and would cause no problems. As I stood there, I saw a line of students walking towards me. They appeared like the other classes. However, as they got closer, and I could distinguish their faces, one student stood out. It was a student on the shorter end of the 5th grade spectrum of heights, but what caught my attention was that this student was wearing make-up. The student looked as if the student was made up for a performance of Cats. The student was wearing eyeshadow and blush that was immaculately applied. And, I thought to myself, “Why would a 5th grade girl get all made up like that?” Anyways, as I welcomed them into class and they entered, I got a closer look at the student and my spider senses started to tingle. The student that I had assumed was a girl did not seem like a girl. Perhaps, it was the way the student carried his or herself. Then I thought about all the news on transgender students and became worried. My understanding on the issue was that I needed to be very careful how I addressed or referred to the student during the class.
I began class as before, but in the back of my mind, I kept thinking of the student. During a question and answer portion of the lecture, I called on the student and was informed that the student’s name was “Asher,” which did not help me out in trying to determine how Asher wanted to be referred to. So, I worried even more that I would refer to Asher in an inappropriate pronoun.
During, the lecture, the class got on a good roll and was engaging on the topic and I was getting so caught up in the discourse that I let my guard down. I referred to a point that Asher had made earlier by referring to Asher as “he.” My heart stopped. And I looked to Asher and Asher just started at me. I mumbled an apology and then corrected myself by saying, “I mean what Asher said.” I felt so ashamed.
After a successful class, I dismissed the students and I plopped down into the teacher’s chair. I felt so bad about what I had done. I felt like a failure. I tried so hard to be sensitive to Asher’s situation. Fortunately, at that time, I had a break and I replayed the situation in my mind over and over. But, the funny thing was that when I looked to Asher’s face, I saw no emotion. Perhaps, Asher was used to the mix up. And, then I thought I might have misinterpreted the situation. Maybe, Asher did not identify as a girl and was made up because he had a performance in a musical after school. Then I thought of how difficult it was today for teachers to have to navigate simple language such as pronouns.
After work, I went home and did some research on gender neutral pronouns. This is what I found:

Source: https://www.uwrf.edu/Inclusivity/Resources/genderpronouns.cfm
This worried me even more. How could I possibly remember all these?
Independent of my personal beliefs on homosexuality and transgender issues, it is critical to me to create a classroom environment where all students can feel safe. But, it seems we have created so much complexity in the classroom dynamic that it is so very daunting to be able to do so.