This is a sticky situation and hard to diagnose via forum... however, there are some things that you mentioned which are very similar to me.

1. The noise sensitivity. This is something many people with bipolar experience, yet it isn't listed anywhere in the DSM-IV.

2. The uncontrolled irritability, outbursts, and guilt even as you are yelling. I sit in the back of my head, almost in a state of depersonalization, and watch my body say and do things that break my heart as I watch myself hurt others.

You did not mention anything about mania (which is the hallmark of bipolar) or depression... but there are other less sever forms of mood disorders such as cyclothymic and dysthymic disorders. You do no sound as thought you have melancholic features of depression, you seem to have more agitated depressive features.

I would recommend seeking help from a family doctor or pdoc, and perhaps a low dose of an antidepressant, such as Zoloft, which is known for reduction of aggression and irritability.

I hope this helps guide you in the right direction!