OPT奇怪的timeline(1890064xxx)

根据uscis.gov ：

12/11: case was received (至今没变化)

根据myaccount.uscis.dhs.gov ：

12/13: We received your case
3/23: We are producing your card and will mail it to you
3/27: We approved your case
3/27: We mailed your card to you

详细经历：

12/4：USPS寄出材料
12/11：case was received
12/14：收到email说case was received
3/12：网上提交case inquiry（第91天）
3/15：收到inquiry回复说under review
3/23：早上查myaccount.uscis.dhs.gov发现还是received，打客服电话然而并没有什么卵用，打完再查居然发现状态变成producing card了（第102天）
3/27：状态变成了mailed
3/28：注册了USPS的informed delivery
3/30：收到EAD卡，但是当天早上并没有收到informed delivery的消息
4/2：收到approval notice