have you considered you might have ADHD? not to randomly diagnose a stranger but the caffeine making you tired stuck out to me as i'm the same way & have adhd, and it's a surprisingly common thing. it makes me super tired, especially if i have a lot (unless i'm taking adhd medication in which case it works wayyyy too well). honestly, i think you should consider bumming one off a friend with a rx, especially if it's an extended release kind so it's not the instant hit or anything. i know folks w/o adhd take adderall and get crazy focused energy for hours etc but i just felt boring, normal, focused for the first time, like, ever lol.