Should I be getting a partial education tax credit?

The usual reason is that you had so little tax liability that it only took some of your education credit to wipe it out.  Most of the education credit is not refundable.

Furthermore, A full time unmarried student, under age 24, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants.  It is usually best if the parent claims that credit.