heyy,look i get school can be stressfull but all u gotta do is take baby steps, if ur tense because of the studies, dont leave them for the end, start putting little pressure on you and you'll be surprised how at ease you'll be in the end. About co-curriculars i think you should make a routine and adhere to it. I'm in 12th grade and i play basket ball, i always wake up early to practice for it cuz i have school from 730am to 3pm. so make a routine, a time tabke and adhere to it.