I use to drink that way too Spen. It's pretty common I think...
unfortunately by the end of my drinking I'd done the inverse - 3 1/2 weeks on and 3 or 4 days off cos I was so ill.
Like others have said - the only way to get out of the cycle is get out...stop drinking.
If you can't do that by yourself it might be time to give a recovery programme a go mate?
D