I would advise against the beers in the rucksack dude, I have been there way too many times.
You may feel 'something' for a brief few moments when the first few cans go down and the promise of having 'something' happening and feeling a release from the undescribale feeling of mundaneness of your day lifted but no-sooner as that 'something' appears it has gone and you will be likely stocking that rucksack back up with enough to see ya right for tomorrow as well. Before you know it you have cleared all of your beers and you have let yourself down and your parents and thus your feeling even more hopeless and another 'drunk' seems like the only escape.
I have played that scenario out way too many times and it is incredibly lonely when your only 'friend' comes from a can.
But only you can decide to not drink and it's your call. Your situation reminds me of mine in many ways, booze is not your friend but in actual fact your worst enemy. I am only just beginning to see that now.