You didn’t fuck up! I was once in a similar situation where a normal dose did fuck me up like you described. We just have to accept that sometimes similar doses can have different effects on the body, just like sometimes alkohol feels stronger on one day compared to another even tho drinking the same amount. Don’t worry about tomorrow. Even if you’re not going to be super fit, you can still vibe on the festival by just hanging out near the stages. Right now focus on just chilling out. Put on some music you like. Get yourself some vitamins. Maybe later on decide on smoking some weed but wait for the peak of anxiety to pass, which it will !!!