How do I avoid repressing feelings?

I am sorry about your loss of your mum. Grief is a part of this life that is incredibly painful. We all experience this grief at some point, and losing a mum or dad can be intensely emotional. I would read your concern as more of a grief/loss issue than repressed feelings. The reason I say this, is feeling a lack of interest in most things could describe depression, which is one of the stages of the grief process. To be sure, I would ask you if you have had a pattern of repressing emotions, or a history of trauma, either of which would inform my perspective. For the purposes of this response, I will focus on the probability that you are experiencing depression due to grief.

Perhaps you have heard about the 7 Stages of Grief.  In case you have not they are a series of emotional experiences common to people who are grieving. Most people will experience the following emotions/stages during the grief process: shock, denial, anger, bargaining, depression, acceptance and hope, and then processing the grief. And these stages are not experienced in a specific order, they are unique for you and the relationship you had with your mum.

It is typical to feel some depression during the grief process.  Depending on the relationship you had with your mum or how she died, you may experience some of these stages longer than others, repeat some stages or experience them in a different order. This is a process that must walked through, it is part of being human and loving people.  

Having supportive people, friends and family, are important during this time. Allow yourself to lean on healthy, positive people in your life for support and encouragement. 

Finding a way to honor your mum's life, to express how you felt about her is an important step in processing grief as well. 

Also a licensed therapist can support you, educate you about the grief process and screen you for more troubling symptoms in case the depression worsens. A person with depression due to grief may still need professional help for depression.