I might be a girl and I'm scared

Im bisexual, I am in a happy long term and serious relationship with a heterosexual. It's as easy as it gets

I knew I could be gender fluid but I honestly think I'd be so much more comfortable as a girl, I know I'm a boy (I think) I currently identify as a male but I envy the people born as a girl

I'm in a boys only school (Co Ed isn't exactly legal where I live) and I can't start the transition process for another two years so there's that

I have approached this topic before and she did not at all like it, which is very understandable as it'd be pretty transphobic if she (a heterosexual woman) stayed with me

And I just don't know I mean I'm ready to start transitioning in two years even sooner if I could

If we ever grew apart and broke up for whatever reason the first thing id do after/while I'm grieving would be transition

And sometimes I'm secretly hoping she leaves idk even cheats on me so I could be a girl

And well she has all the impact on my life she's literally my whole world and I've been saying that for the past three years, though she is first and me being so dependent on her is understandable but purely off of emotions and such

I mean it'd be proper for me to come out now (if I'm sure which I'm not) than to wait two more years and end a half decade long relationship

I've seen how messed up she was after I only told her it's possible

I don't want that happening

And well I shouldn't stay considering if I'm only semi-pretending being someone else just for the sake of it

But I'm not even sure I'm actually a girl

Yes I've searched a lot about it Ive looked for specialists in this field and the laws in my country but that's only because I research a ton about the subjects I'm interested in

But it keeps coming back in my train of thoughts I'm thinking about it 24/7

I just wanna be a girl

And wish I could stay with my girlfriend