Hello,
Two things:
a) It makes sense.
b) Bipolar disorder is becoming the new catch-all diagnosis and is beginning to be really over-used.
That being said, given your history, he very well may be right. One way to find out is to see if you respond to certain medications...so you very well might want to go along with him for awhile. Or you could go to a board-certified psychiatrist for an evaluation.
I was just writing a post to Leomia in which I was talking about the newer research that is now including more categories into the over all umbrella of bipolar disorder, or as it used to be called, "manic depression." There is BP2 and BP-NOS (not otherwise specified!!) and I have a whole book on depressions that don't respond to medications that are now being called "soft bipolar." The general public thinks of mania as the classic type which was always defined as euphoria or grandiosity (grandiose thinking, thoughts). But there is also hypomania which often presents as agitation, rage, irritability, anger, trouble sleeping, etc.
Often BP is first diagnosed when someone has been battling depression for awhile and goes in to seek treatment. S/he's given an antidepressant and after taking it awhile, starts exhibiting other symptoms...can't sleep, can't control anger or agitation, flies off the handle for no reason, has racing thoughts...etc....and then discovers the med has flipped them into hypomania.
Also it is very common for those who have BP to self-medicate. Something between 60-75% of BPs use drugs or alcohol in an attempt to control their symptoms. Unfortunately, this almost always makes things worse...but when they get on the proper medications, the need to use lessens or goes away. This was the case with my son who is now 25.
There are two very good websites where you can go for accurate information. One is the National Institute for Mental Health and the other is ****.org. **** is a national organization that has state and local chapters in every state that provide educational programs, support and is also an excellent source for referrals.
Hope somewhere in all this information you will have one of those "a-ha" moments where something will sound like what you are experiencing. Bipolar disorder is the most treatable of all the mental illnesses. I hope this will put you on the path to recovery and that happy life you're looking for.
Welcome to this board. Please post with your questions and concerns.

Tsohl