Zen...lovely lady...please don't be so hard on yourself.
Everyone has given you good suggestions, and I hope they have helped you.
Holmes is spot on about handling the interviews. Keep it in your head that the interviewers are not asking for your life history...they are interested in your ability to do the job and interact with the children, the other staff members, and possibly the parents.

You know you can do this, Zen.
Give yourself credit for what you can do--and let that show in your interviews. The way you present yourself to them is important; it's their first impression of you. It's expected that any applicant will be a bit nervous...
Relax and be yourself.
You are good, ya know? You wouldn't be pursing this if you had any doubts about your abilities to handle the responsibilities...let your confidence show...it's not being egotistical; it's recognizing your talents.

In Peace