It is actually very unnatural to not feel any anger. Anger is a sign that something is not right. If you have not felt any anger, it is probably because you had been taught to repress it.
From personal experience, it is going to suck for a little bit. When I finally got in touch with my anger, I had been repressing it for 25 years and it felt like it was seeping out of my pores. It felt so unnatural to who I was, but I could not stop it. positive side of this is that I was working with the therapist and I was able to come out the other side. I now understand my anger a lot better and I know how to handle it when I do get angry. It becomes a passing emotion now and not one that I get stuck in.
Remember that this is temporary. Find places to channel it. Work with your therapist to get to the root of why you have all of this anger built up and address it there. It’s important that you treat it at the surface level, but if you don’t get to the bottom of it, you won’t actually integrate it and transform it.
This is part of continuing to grow into a whole human being! Exciting stuff, although it is hard and not always fun. I believe in you though!!