Héhé, it seems that I'm a bit overthinking this name question as it's only like a nickname and I will not put it on official papers (by the way, Kate, I love your triplet story !!!).
I've had many nicknames through years, but people calling me "farfadet" (a kind of elf) or "cow-boy" with no particular reasons would be very weird
It's, funny, MugwortPsychonaut, that you speak about a stage name because I'm actually a musician (but in classical music it's not so common to use stage names). Ah et oui, tu lis bien, "super chou" veut dire "super cabbage" mais dans ce contexte ça veut dire "super cute"

Interesting that for you, Cynthia, being called by you birth name was odd when I'm afraid it would be weird for me to be called by another name.
I think the easiest way would be to choose a short version of a name that can be both gender. Like Alex, that can be short for Alexandre or Alexandra. (But not Alex, because my most stupid cousin is called Alexandre...)
I also love the idea of asking my parents to give me a new name but... I think this will need time as they don't know anything.
Oh and because many of you shared how they picked a name for here, mine is short for pterodactyl which is my favorite dino