did i just screw up this interview?

Don't worry about the timing. Interviews are fluid and if the person got all of those questions answered, then you are just fine. Maybe you did a better job of answering the questions and did it at a faster pace than the others. You won't know for sure until you hear back from them, so just be patient.

Don't feel so negative,the interviewer may have had all the information they wanted by the time 12 minutes were up.