YOU are a CHILD.
You are not going anywhere without an ADULT involved. Usually a Parent.
Your Parent shows their ID at the check in .
Each Airline has their specific requirements. LOOK for the information for YOUR Airline. for the Check in Requirements.
The Security check point is the next stop. They have their rules. Slightly different.
TSA does not require children under 18 to provide identification when traveling >>>> with<<<< a companion within the United States. Contact the airline for questions regarding specific ID requirements for travelers under 18.
Forgot Your ID?
In the event you arrive at the airport without valid identification, you may still be allowed to fly. The TSA officer may ask you to complete an identity verification process which includes collecting information such as your name, current address, and other personal information to confirm your identity. If your identity is confirmed, you will be allowed to enter the screening checkpoint. You will be subject to additional screening, to include a patdown and screening of carry-on property.
You will not be allowed to enter the security checkpoint if your identity cannot be confirmed, you chose to not provide proper identification or you decline to cooperate with the identity verification process.
That you pay Adult Fare does not give you a magic birthday. You are a Child. A person under age 18