I’ve never had an issue dressed en-femme in clothes shops but I think the assistants probably have bigger things to worry about than someone 6’2″ trying to walk in heels (OK only did that once).
I had to vote “other” as the teen would neither identify as son or daughter. We aren’t sure what to use as gender neutral options seem thin on the ground. Using “child” seems inappropriate for someone their age. One website did suggest “spawn” as an option.
That aside, they are very comfortable with my dressing and it was an amazing day when I told them and they gave me a big hug whilst dressed.
Next step is figuring out how to tell the SO without the world falling of its axis!