Re: "Messed Up" doesn't even describe it
Em I think the first problem is that you are looking for there to be something wrong, a great many people do this and despite the initial relief that is felt problems arise when these people start to go on medication. Medication should always be the last resort or at least for the most part depending on the specific sictuation.
Moving on however to what you have written; it seems that yes, confidence or rather the lack of it may indeed be a large problem for you but luckily however there are many great books and websites in which can help you build this up and of course there is always a therapist.
More important I feel is the anger issue. People who say that they have problems with anger tend to mean that they express anger in their daily lives, more often or not in a physical sense. However this isn't the only type of anger issue, some people much like yourself keep there anger to themselves and it screems inside their heads growing worse and scarier for the person experiancing it. This is a problem that isn't too uncommon and so help is available.
My advice for you is to go to a different doctor and ask to see a therapist (when speaking to the doctor focus on the anger issue), once you are reffered then your therapist will give you advice and excercises to do in order to build up your confidence and deal with the anger.
Over time all will come clear and you can live life peacefully knowing that you are exactly who you are, that you are capable of all that you are capable of and that your own likes and dislikes make up just who you are.