I'm still wetting the bed at fifteen years old
What do you think is causing you to wet the bed?
It happens all the time and so easily.
It's good that you aren't ashamed to admit to this. As a teen this isn't normal and you should ask a doctor about it.
I'm scared that I might be diagnosed with some disease.
I understand that it's scary, but it's better to know what is wrong so a doctor can treat it sooner rather than later.