Kindeyes, you are describing EXACTLY how I have been a large part of my life. I have to laugh at "I would become pretty darn bitter if someone didn't appreciate all of the nice things I did for them.....even if they didn't ask me to do them in the first place." This caused a lot of problems for me even in friendships.
I do also realise that it does not describe me anymore. Somewhere along the line I lost my co-dependency. The flip side of the coin is that I sometimes look at myself and wonder when I became so hard, so I guess somewhere within I still think co-dependency is a good thing. I also noticed how few people I am still friends with from those years. I used to be friends with people who I either felt sorry for or who I felt inferior towards. Nowadays my friendships are on a more equal basis.
But your list? Yes, that was me down to the last statement.