@YuuAiko,
Hi!
Your English is great, very easy to understand.
Note: I am not a doctor and I am not trans.
I don't think it's a "phase". But I do think it's related to your age/time of life. Here's what I mean by that.
At age 17, and born with (presumably) XX chromosomes, you could, with good fortune and science willing, live another 80 years. There is an enormous amount of pressure to decide on the course of the rest of your life,
right now. You are probably also getting this kind of pressure to choose a career, a place to live, etc.
That's nuts.
There's no way any of us can know what will work for us for 8 decades. Hell, a lot of people don't know what will work for them for the next 8 weeks.
The term genderfluid is, I feel, spectacular. It's telling yourself and the world: "I don't know yet."
Be career fluid. Be living space fluid. And if you're not sure about the next 8 decades or even the next 8 minutes, then if you absolutely,
must put a label on yourself, then genderfluid is pretty much accurate, I'd say.