Welcome to the forum. This community is full of kind, caring, friendly, nonjudgmental people.
I am not a medically trained person, I have been a teenage girl , a quite a few decades ago and have lived experience with mental health.
As you have written and know being a teenager is full of highs and lows and exaggerated emotions so working out what is happening can be difficult and take time.
Have you spoken to your parents or to a trusted teacher or a school counsellor and if not would you think about that or speaking to your doctor? You mention you don't want to go to school, but are you managing to go to school despite not feeling like going?
Crying as a teenage girl is very common I would say .
I can see you an intelligent and thoughtful person.
You have written a very clear and well expressed post.
I have asked a few questions so I can help you some more.