Hi and welcome to beyond blue.
I have 2 teens - one who finished high school this year and other completing year 10. School can be best and worst of days. Something I have worked out with the dramas we parents have to deal with, and most of it is unpleasant. At the current time my daughter is completing exams. There are apps like smiling minds that you might be able to look at to help you relax a little bit regarding school work?
I am wondering however, if you are able to speak with your parents about how you are feeling? Or perhaps the school counselor or chaplain?
Also you could look at the Anxiety and depression checklist (K10) here...
Even if you have nobody to talk to, know there are people here who care and will listen to you. You are not alone. The other advantage of writing here that other people will respond to you posts.
I know you are under pressure with school work, but good luck with it all, and I hope to hear from you soon,