Everyone feels a bit this way after interviews Poppy. We start to think what we should have said instead of what we did. It's those negative thoughts patterns 'Should' keywords instead of 'Could' and we end up with 'What If' thinking as well.

Its not productive, but people without anxiety disorders also do it so its not something that comes from anxiety, its natural negative thinking. So, try not to dwell on it too much.

Whats done is done so all you can do is learn from it (be constructive though) and see what happens next.

I take it from your age & education that you are only really starting out in your career so I would expect any interviewer to be taking that into consideration. Its also important to remember that not all employers/sectors value the traditional aspects of a person i.e. qualification or experience, as they may use questioning to determine core values and your abilitiy. Remember that there are plenty of people out there with good levels of education yet are poor in work and there are those with loads of experience that are mediocre. So, whilst both of these factors are important, you still have loads to get across in your values and abilities so maybe you didn't do as bad as you think despite your lack of experience in certain areas?

If you get questions about areas you haven't really covered, you can substitute with experience that demonstrates the same skills. This then shows a prospective employer that you have the ability to perform the role despite needing some time to adjust. If the industry doesn't require specific experience e.g. to be a plumber you need to be a plumber first, then this can still get you the job.