I was 17 for 6 months when my mom filed her taxes I was still 17 . She just recieved her stimulus check and 500 for my little sister and nothing for me .

The $500 payment is for children under 17.  You would have needed to be 16.  

We also believe it may be based on the age of the child this year since the payment is technically an advance on a credit for 2020, but we have yet to be able to confirm this information.