For what it's worth, your English is wonderful, and you are articulate and communication is key with au pairs. That is the only - only! complaint I have with mine, which can lead to more because she does not understand my written policies, and it is my fault for not wanting to confront her on some of her mistakes because otherwise she is so wonderful and I can take some faults in return for how diligent, loving, and generous she has been for our family.

(there - a smiley for you).
That said, I definitely limited my search to someone who has not just "babysat", but also worked full time in child care at least for a few months. I also only will interview au pairs who have lived alone away from the family for some time so that they are independent enough to come to a new country without collapsing from the change.
Best of luck - polish up that application with those characteristics that people have advised on throughout, don't take any words too harshly or seriously, and come with an open mind and flexibility to adapt to a new family and environment.