NOT A TEACHER
Hello, Maykarlin:
I just thought that you might like to know that at least one expert would probably recommend that your title read: "My English teacher may have made a mistake."
This expert reminds us that "might have + past participle" = Something could have happened but we know that it DID NOT.
"may have + past participle" = Something could have happened but we DON"T KNOW YET.
Don't feel bad, though, for he says that even many journalists and professional authors make this mistake.
When you posted your question, you did not know yet whether or not your teacher had made a mistake. That is why you posted your question.
****
That expert gives this example of the correct use of "might have + past participle":
The poet Gerard Manley Hopkins destroyed the original copy of one of his poems.
"If Hopkins' work had met with a warmer reception during his lifetime, he might have felt it worth preserving." (P.S. We know that he did not feel it was worth preserving, for he had destroyed it before that sentence was written.)
Source: John Honey, Language is Power / The Story of Standard English and Its Enemies (1997).