Everyone is right on par here. Physicians often prescribe medication for uses other than what they are approved for. This is called off-label dosing and is almost always backed by evidenced based approaches. The FDA does not permit pharmaceutical companies to mention anything about their off-label uses to physicians or in their advertising.

For instance antipsychotics are marketed for the treatment of Schizophrenia and acute mania in Bipolar Disorder. However, they are prescribed more in low dosages to treat depression and anxiety.

I'm sure if you tell us the dosage of your medications it will be quite clear they are being used for off-label treatment of depression and anxiety instead of Bipolar Disorder.

The important thing is that you use these medications as a stabilizer and a way to make therapy more effective. Have you made a plan with your therapist to discuss how long you will be on these meds?