The danger of self analysis is that you may unconsciously alter your behavior to conform to your diagnosis. We all have mood swings, are you exaggerating yours to conform to your diagnosis? By all means seek professional help, but even there the danger exists that you will unconsciously try to influence his decision. "Doctor, I have wild mood swings, etc."
I suggest that before seeing the doctor you attempt to control they symptoms. Avoid mood wings, snap decisions. etc.
It is not unlike the danger of self diagnosis of physical ailments. If you convince yourself that you have a brain tumor, you are likely to feel pains as you imagine it growing in your skull. etc.
I think that your frequent masturbation my also influence your mood swings, as is alters your hormonal balance. Take a look at the "Guilt after masturbation" thread in this forum. Are you going to tell the Dr about your masturbation?