Hi Ellie -
I too have a hard time expressing my feelings for the same reason as you. My family NEVER let me share my feelings. Any sort of emotion was being a "bad girl". I think no matter how hard you try, there is always that "inner voice" (my Nmother in my case) telling you that inside anytime you feel something. It is a constant effort for me to speak louder to myself inside than her voice. I find with time it gets easier but I'm not sure if the voice will ever go away completely, maybe just minimize to a whisper.
I was looking for some outlets to my anger a few weeks ago during a very hard time personally. I came across a great link that tells some wonderful ideas about expressing anger in a healthy way.
http://www.coping.org/anger/workout.htm#stepsScroll down to "healthy anger work out".
A few of the things that I enjoy doing when I'm mad are:
water balloons (actually I got my entire family in on this one a few times - my 3 year old loved it, surprisingly do did my husband)
writing letters (NOT sending them but truly writing what I feel)
poetry (again, just writing what I feel at that moment)
hitting the bed or pillows with the big foam bat (I usually go from raging mad to laughing by the end)
Who cares if you make a fool of yourself? I have found I get my anger out the best when I act like a complete fool and totally "lose" it (without harming others of course). Another idea my therapist had was to go somewhere private and scream as loud as possible. I would love to do this one but don't know of a place that private. I also would love to get some cheap glasses or old bottles and just shatter them, but with little ones around I'm afraid of the shards.
These work for me, you will just have to find out what works for you. I have found it very healing to do things that I enjoyed as a child to help me heal in other areas. Examples: Playing paperdolls with my daughter, reading my favorite children's books when the kids are asleep, coloring, etc.
I remember a while back someone posted a link to an article about "healthy vs unhealthy anger". Don't have time to look it up now but maybe that will spark someone's memory to post it here.
Big hugs for healing -
Michelle