I'm a full time student that hasn't been supported by my mom through university. My mom isn't be claiming me on her taxes. I'm not sure why I don't qualify for the A.O.C.

TurboTax is basing your eligibility for the American Opportunity Credit on the answers you've provided in the interview process of preparing your return.

The eligibility requirements are spelled out in the TurboTax Help article Who is eligible to take the American Opportunity Tax Credit?  If it appears, based on a reading of these requirements, that you're eligible to claim the credit, try re-inputting your relevant information.

In TurboTax Online,

1. Click the Tax Tools dropdown in the left pane, then Tools
2. In Tools Center, click the Topic Search box, enter 8863, then select 8863 - education credits and click the GO button

From here, you can review your previous answers.

For additional information, please see the TurboTax article What Is the American Opportunity Tax Credit?