Here's a good way to think about the issue.

Your teacher knows better what was good and bad about every speech than a lowly student like you. Your teacher has a better understanding of what was best looked for and evaluated in every speech than you do. You couldn't see your speech from a third-person perspective, whereas your teacher did. Therefore your speech must have been pure f*ing awesomeness and the fact that your classmates didn't do as well only shows that their preparations were inefficient and misguided. Therefore your academic prowess exceeds that of your fellow students and you have no reason to feel bad for doing well.