If they do not ask you if you have questions and you do not find time to insert them, it does not mean the interview went poorly. The interviewer could be particularly interested in the conversation, causing them to use up the time allotted for questions.
Try to show interest in the school with your answers to their questions. Answering their questions while demonstrating interest will help you avoid feeling like you did not make an impression. The ability to do this is where interview prep becomes essential.