Your exams don't start for another week and a half - you have plenty of time. ;-) It all depends on how you "spend your time" between now and the start of the exams.
You want some suggestions --- here goes ... You are in school until 3:00 or 4:00 Monday to Friday. Tomorrow is Sunday --- no school.
Don't look at the eleven exams ... look at only some of them tomorrow. Pull out your books for the first one and read and review for half an hour --- then get up and walk around ... then do it again for another half hour. Then, get up and walk around. Think positive --- "I CAN remember ... I WILL do well." Give yourself an hour's break --- get outside and get some fresh air.
Then, pull out your books for the second subject and do exactly the same thing as above.
Then, do the same for the third subject.
Then the same for the fourth --- and the fifth.
You have taken Sunday and reviewed five subjects! You've used up fewer hours than you ordinarily are in school but have accomplished a lot!
This coming week, pay attention in each class --- LISTEN, ASK QUESTIONS, WRITE NOTES TO YOURSELF. You wrote that when the teachers talked, you "didn't take any notice." Change that starting on Monday.
Then, when next Sunday comes, do exactly what you are going to do tomorrow ... only with five different subjects and add a sixth so by the time next Sunday night comes - you will have reviewed each subject.
During the time between now and your exams, cut down on your tv watching, text messaging, phone calls etc. Look at it this way --- your JOB is to go to school. Your JOB is to write exams. Your JOB is to do well in your exams. It's so easy to say "I think I'm depressed" but you won't know that unless you go to the school nurse or your family doctor and even if you are depressed, you can still do your job. ;-)
Think of it as preparation for your job when you graduate and get out to the work force. Your boss will tell you that you have to have a presentation ready in two week's time. You can't plan on doing that project/presentation the night before --- you have to do a little bit each day. So it is with your present job (being a student).
If you take one step at a time, one subject at a time, you'll find yourself sitting in the classroom, writing your exams, not stressing out, being confident and getting good grades.
Yes, it's difficult but your excuse of "I don't have time" is hogwash. You do have time --- you must now decide how to spend your time between now and the exams ... will you spend it wisely - or will you spend it with your friends, texting, watching videos/tv, playing games etc or will you do the grown-up thing (you're a teenager now --- time to begin to grow up and look at the responsibilities that come with growing up ... like studying for exams, listening in class, doing homework each night, taking good notes etc).
Good luck! ;-) You CAN do it! I believe in you. Do you believe in you? Hope so. ;-)