You are torturing yourself unnecessarily. As a fifteen year-old, why would you expect to ‘know for sure’ all the truths of Torah? How are you supposed to ‘know’ who created the world?!
You don’t how an airplane flies or how an antibiotic works. You’ve never seen a germ or a virus, and probably don’t know where your spleen is or what it looks like. Does any of this matter? No, you live your life based on knowledge received from the past without need to reinvent the wheel.
G-d created the world and gave the Torah on Mt. Sinai unless you have witnesses to the contrary.
The best and wisest minds among our sages, every one of them smarter than Einstein, studied the Talmud for three thousand years without doubt of its origin and you are not sure!
So you feel guilty as if you are responsible to prove or confirm cosmic truths! Get real. Relax. It’s not your job. Your job is to elevate yourself to a more productive, noble, respectful life every day.
Work on that. I guarantee you won’t regret it!