Hi I've applied for nursing and had 3 interviews so far.
All of my interviews lasted about 15 minutes (one was 10) and have had offers from 2, (I am waiting back on one uni) I don't think it's necessarily the length of what you say so much as the quality.
It is out of your control now regardless and you can use what you have learnt from this interview to improve for your next.
Good luck x