Stranded in a desert, but the sands of time elude me

I have overloaded myself this year; i've never been so sure of it as right now. in the past, when i used to say "oh crap that's too much for me to handle", in my mind a voice would go "come on, it's ok, gonna pull through somehow". now, that voice has been muted and all i hear is a much louder voice saying "TOO MUCH TOO MUCH TOO MUCH". out of 5 school days a week, i only have one day with no after-school activities. even saturday mornings have been taken up by pitch trainings. whatever laid-back optimism i used to have about just about anything else has now left me; now i only see all the different ways in which i could possibly fail. i doubt i will have the energy to properly do homework after coming back from  training, and going for H3 will almost certainly bring more homework and research to the table. for the first time in my life, i feel despair about my academic future. A levels; A divs; H3; OGL... what the hell was i thinking? i cant handle all this at once; im going to fail miserably for each and every one of them. from now till then end of term 2, my life has become a ticking time bomb, and it's just a matter of whether i can avoid the hairpin trigger until after i finish up with A divs and H3 and focus completely on A levels.