"Feb, 09" is not my real birtday!

Since I was born, I don't know what is my birthday. My parent told me that I was born in dragon year, it must be once day in 1988. But when I go to school around 6 years old, teacher asked me: what is my birthday? I don't have the answer. Then, teacher decided to use standard age for me by following the policy of ministry that children must be at least 6 years and give the day of 9th and month 2th. Since then, I have used the birthday as my formal work. And now, it is used generally and become more formal in my life. However, it is not important on birthday, right? that is just what I want to say in a day before my birthday to reveal why my age like this :P