i can probably relate to your situation alot, although i use my obsession with guitar for a motivation, I'm doing all hard subjects at school so i know i have to do homework and stuff. Maybe discipline yourself and say don't play guitar until all your homework is done for the night. And it'll only take a couple of hours for your homework then you have hours and hours to spend on guitar. I have so much homework but i still manage to find at least 3 hours a day to play guitar