I am trying to forgive my mother for some things that happened years ago. I am not feeling very angry now and so I am wondering: Am I over this or might I be repressing my anger? How can a person tell if they are repressing anger?

One test of repressed anger is this: As you think of giving the gift of kindness and compassion to your mother, do you feel free inside to give these gifts to her?  If the answer is yes, then you may be over the hurt (whether by forgiveness or some other means).  If you are hesitant to give these gifts to your mother, then you likely do have repressed anger. Starting a forgiveness process and being patient with this may reduce the anger.