Elfina I hope you don't mind me adding a bit of my own path to finding anger, because like you, it was a struggle for me to find it at first. I agree with cailindana that it is an immense force for healing, certainly in the beginning stages.
I used to just feel ashamed too, it was like anger didn't exist in me. If I was ever angry at all it was just myself. After a lot of pondering why, I came to the conclusion that:
a) I had believed all the negative things said to me about who I was, and so truly believed I was worthless and subhuman. I had never really taken time to re-evaluate this and develop my own ideas of who I was.
b) It had been in no way safe to express outward anger, ever. So the only outlet I ever had for anger was inward, and I was unconsciously keeping it that way.
Secondly, I stopped using any negative mental language toward myself. I used to have a constant stream of criticism and insults going in my head, "You're so useless, you even messed that up. What a waste of space. etc etc"
I made a rule for myself that anything I wouldn't say to a friend in pain, I wouldn't say to myself. And then I gave myself permission to be the defender of that rule. So anytime a negative voice popped up, "You can't do anything right..." I would 'shout' back at it in my mind. "Stop it! How dare you talk to me like that!" And then I would console myself just as I would a friend, "You don't have to listen to that. You're trying your best. Keep going."
Finally, I re-evaluated those parts of my past with my new mental dialogue, and my new 'inner defender', and I imagined how I would feel if I had seen one of my friends there as a little girl, being abused the way I was.
And then the rage came... oh boy did it come.
The anger isn't the final step (at least it hasn't been for me), but it healed a lot. It was like a cauterising blaze swept through what had been an infected, gangrenous, weeping wound, and left it ragged but clean and pink, a foundation for regeneration.
I didn't mean for it to turn into an essay
, but I hope it may be of some use to you, and anyone who has yet to tap into their own powerful, healing anger.