There's always the issue of how you think you did, and how your results came out. There's four possibilities:
1. You think you did well, and your results reflect it. Par-tay!
2. You think you did well, but your results do not reflect it. Stuff happens sometimes, it's a subjectively judged sport, and results are not always consistent. But if it becomes a pattern, you'd better re-evaluate your dancing.
3. You think you did poorly, and the results reflect it. Well, at least you had fun, got to chat with people, maybe met some new friends, and hopefully the buffet was decent. Work with your instructor and your partner, figure out where you need to improve, and better luck next time.
4. You think you did poorly, but your results are good. This is a tough one. Maybe you just got lucky this week. But has this become a pattern? Maybe you're not giving yourself enough credit. Maybe you're spending too much time worrying about stuff that doesn't matter. Or maybe you need to look for tougher competition so you can get a better read on how well you are actually dancing.