I have an genderfluid teen. We're about 6mo into being partially out. Pretty sure it's not a phase at this point, and I wasn't really surprised by it when they came out. They'd been questioning it for a few years now and we could kind of tell.

They prefer non-gendered or male pronouns / their male name, but have decided that with some older family members and random people they aren't going to interact with often that it's just not worth the effort to correct them. They've also said that around family is where they feel most comfortable being identified as female, so female pronouns don't really bother them in that setting.

It depends on how your kid feels about it, though. If it's important to your teen, then I would keep correcting people who didn't use the right pronouns. If they refused, they wouldn't be invited around my kid.

Personally, if people are respectful of my child's choices when talking to them, I don't care how they refer to my kid when they're not around, because I realize it's a big adjustment to make and it takes time. If they're still doing it a year from now, I might take issue with it.

For my teen, the biggest thing was being able to look how they wanted, which in our case meant a short haircut and looser clothing to give some ambiguity. Being able to use their chosen name at school was also important to them.

I have to admit, I love the haircut. I was skeptical going into it, but it looks super cute on them and the amount of self-confidence they've gained since getting it cut is amazing. It really does fit their personality so much. It's the same way I feel about their chosen name. It's one we never would have picked, but it's smart, creative, and fun, and it just fits. They outdid themselves on that one.

And what happened to girls who didn’t feel feminine just being tomboys?

Eh.. it's different. It's really hard to articulate how, but it is. I was always a "tomboy" in terms of my actions/interests/behaviors, and I never felt especially feminine, but it never bothered me that I was. I never had a desire to look different and my sense of self wasn't affected by it.

As for therapy, it can be useful for some people (parents and kids), because this is a lot of stuff to work through. If your kid has issues with body dysphoria (common in kids who are gender non-conforming), therapy can help with that, too. It's a useful tool, but it's not a necessity for everyone. You know you and your kid best.