@Tcof
If it is just a delusion then who was her girl/boyfriend? She said she had a boyfriend in the other world right?
Let's assume that she suddenly wake up in the middle of the street and realize the reality of yuri world. Every boys/males existed was a fake data that was installed into her head. Her little bother was actually little sister, and this could make sense, because the sister said MC has treated her difference lately. Obviously, when you family got swap gender, it really hard for you to look at them like the way you used to do. Also her sis seems like a brat, which is a bit similar to a boy traits. So first point makes sense.
But what about the boyfriend? If she wake up, not being swapping away with the other version from alternative reality, then the boyfriend will become girlfriend right? They should have continued dating and stuff. But no signal of it. Not at all. Like the boyfriend is swept away from the existence. So the second point some what has defeated the first point.
Moreover, if I recall correctly, there is still another character revealed lately and hasn't completely shown up yet. I think that girl is actual twist in here.