Norman
One suggestion, you can rehearse the interviews in advance . . . .
This is what i suggest . . . .
based on interviews you already had
1. create a questionnaire of possible questions that they have asked you in the past or that you think you would ask another person being interviewed . . . . (in other words, switch the roles and put the hat of interviewer and think about the questions to be asked .. . .)
2. respond to the questionnaire, first in writing . . . and then out loud, this should allow you to compose your thinking and your vocabulary, pronunciation, diction,
3. rehearse the questions/answers by yourself over and over
4. Finally, have a friend or family member interview you . . . .. rehearse this over and over, practice in a similar environment as close as possible to an actual interview . . . .. table, chair, if it is online, computer monitor, mic, video camera, etc, watch your own body language . . . .ask your friend to tell you how they perceived you, correct thinks that you notice are not projecting security and knowledge
overall, the result should be that you will create a mental picture of the setup and the responses, almost like a reflex, your mind and body will get used more and more and hopefully you will not only lose the nervousness but also be much better at your possible responses in the actual interview(s).
Hope this helps.