Oh I am so sorry that you feel this way.
It is alright. I am sure people will see that you were trying to make an effort.
All you need to be is to be yourself and give answers from your heart.
Please don't feel like you are being interviewed. I know that you want to be as professional as possible but the end of the day they are going to leave their children with you. They are as nervous as you are.
Honesty and believability go along way.
Good luck!