Irritability is a symptom on mania. Just not as pleasant as the rest, so it's not typically listed. Irritability is not just found in manic episodes but also mixed.

The symptoms I have found for mania include:
Increased Energy
Restlessness (this IS different from Increased Energy)
Very High Mood
Extreme Irritability
Racing Thought
Talking Fast
Distractability
Poor Judgement
Spending Sprees
Increased sex drive
Intrusive Thoughts
Aggressive Thoughts
High Motivation

...

I hope it turns out the the doctor was wrong as I understand that this will take away your career, which you obviously chose and would not want anyone else going through this. Based on what you have listed so far (although you not knowing the whole list of symptoms could result in you not listing something as a symptom, like if you didn't know a runny nose could mean you had a cold, you wouldn't list it because you would think its not related.) I wouldn't consider it bipolar. I'm hoping that maybe this is maybe just some anger problems and Situational depression (I call it situational because when the situation you're going through is over, the depression is gone).

If you are in denial, Look up the symptoms (in multiple places, one site won't list them all). Take a really good look at your moods and your behaviors. Because the sooner you start treatment, the sooner you can become stable. And look up Mixed Episode... see if that fits.