guys lets just stick to the OP's problem.
and smoking weed doesnt make you a loser, i know guys who do well and work hard, and they smoke once and a while. what makes you a loser is if you let it take over your life.
Do NOT go to prom high, people can just tell and you'll act different around them, wich usually isnt good when your baked cause they'll think your weird.
Go with some friends at least, you wont look like an antisocial person who has no value.
If you KNOW you have game, and you want to go alone, then go for it, but dont get yourself psyched up expecting to pick someone up at prom, you gotta be sure of yourself. you cant have this goal in your mind of picking someone up, then actually getting there and not doing it. you gotta KNOW your gonna do it, or find a group and have fun with them instead if worst comes to worst.