Hi Lascaux,
First of all, a problem with alcohol is neither a moral issue nor an issue of weakness/lack of willpower - it is truly a disease. Science is just at the cusp of formally recognizing this, so don't get caught up in feeling like you're failing people because of some shortcoming that you could easily change if only you had the moral compass to do so.
That said, it
is possible to change. Don't bother with worrying about forever; as the others have said, only worry about today when it comes to drinking. For other aspects of your life, go ahead and plan, but for drinking: make a one-day plan each day that centers around NOT drinking at any cost. Perhaps that means going to several AA meetings, getting some numbers to call if you feel the urge, confessing this problem to your friends (who probably already know)... it can take many forms. You have to be willing to do anything to get there, and unfortunately it invariably means swallowing some pride and learning humility. It's not easy by any means.
You know you have a problem. Don't let it get any worse. You say to yourself while sober "I'd never squander these opportunities", but you've already admitted that when drinking, you let things slide and are incapable of giving anything your all. I know precisely how this is. Nothing matters when I'm drinking except MORE drinking, and more and more and more...
Please look into feasible options sooner rather than later. Future you will be so thankful
