It seems that you are suffering from Dysthymia (Minor depression)
You might be surprised to hear that irritability and anger are often signs of depression. The changes in your personality and your social behavior also point to depression. I urge you to talk to your family doctor, let them know about your feelings, and ask them to help you find a therapist to meet with.
It's also possible that while anger can be a symptom of anxiety, it can also be a cause. People with anger issues often experience anxiety as they worry about their anger issues, and in some people this can lead to further outbursts of anger which cycle back into stress.
Here are my recommendations.
1) It's important that you learn certain behavior modification technique .Although they will take time to master; it's the best way to get over anxiety and depression.
a) Continuous muscle relaxation- As the muscles relaxes, your mind follows suit.
b) Breathing and meditation.
c) Learn calming techniques like massages, gardening, cooking etc.
2) Get professional help if you feel that the symptoms are taking too much of a toll on your daily activity. There are very effective medications, albeit with a few side-effects.
3) Adopt healthy eating habit and follow a good routine of exercises. Avoid alcohol and smoking.
4) Maintaining a journal also helps in reducing anger. Write down the angry thoughts in a journal so that you can read it back and find out the real issue behind the problem ,once you have cooled down.