Thank you for requesting me. While I can't give you a definitive diagnosis over the internet, I can give you some information that might help clear up some of the confusion for you.
In order to be diagnosed with Bipolar Disorder, one must experience either manic or hypomanic (not as severe as manic) episodes in addition to depressive episodes.
Here are some of the criteria for a Manic Episode:
A. A distinct period of abnormally and persistently elevated, expansive, or irritable mood, lasting at least 1 week (or any duration if hospitalization is necessary). (A hypomanic episode can last 4 days)
B. During the period of mood disturbance, three (or more) of the following symptoms have persisted (four if the mood is only irritable and have been present to a significant degree:
(1) inflated self-esteem or grandiosity
(2) decreased need for sleep (e.g., feels rested after only 3 hours of sleep)
(3) more talkative than usual or pressure to keep talking
(4. Flight of ideas or subjective experience that thoughts are racing
(5. Distractibility (i.e., attention too easily drawn to unimportant or irrelevant external stimuli)
(6) increase in goal-directed activity (either socially, at work or school, or sexually) or psychomotor agitation (means you move around quite a bit)
(7) excessive involvement in pleasurable activities that have a high potential for painful consequences (e.g., engaging in unrestrained buying sprees, sexual indiscretions, or foolish business investments)
As you can see, there's some overlap with the racing thoughts and inability to concentrate, BUT there's at least 2 important differences here:
1. Someone in a manic episode can't "come out of it" on their own or with tools to calm down
2. Like you said, people in a manic episode are often unaware of their behavior and don't feel it coming on generally. The behavior is often extreme --buying sprees, sex sprees, eating a lot and very fast, driving fast, talking very fast and pressured. Sometimes there's delusions or at the very least thoughts don't hang together really clearly
People with Generalized anxiety disorder generally don't experience panic attacks, rather they experience intense worry about a wide range of things.
It's possible to have several different anxiety disorders at one time. Depression is a common occurrence with anxiety disorders, and either can follow the other (anxiety can make you depressed and being depressed can make people anxious).
In order to get a proper diagnosis, you should see a Psychologist --besides a clinical interview he/she can give you some assessments in order to clarify the diagnosis.
Here's a bipolar screening test you can take:
Why don't you take the quiz, tell me the results and we'll go from there?