You have already come a long way!
If you are invited to a job interview, you have earned it! Either by submitting a great application and a well-made CV or in some other way made an impression that you will be a good match for the position.
Part of the interview is about the personal chemistry between you and the appointments committee. It can be very difficult to do anything about this.
However, there are many other elements of the job interview that you can prepare for and practise beforehand.