I think I might have ADHD and/or bi polar disorder, I have already been diagnosed with depression and anxiety, I get too nervous to ask my real doctor?

PCP. PCP stands for primary care provider, he or she is the one you should have a special relationship with and feel comfortable talking about everything pertaining to your health. I would advise you to tell him/her about your concerns.
Please see below. If you are worried you might be bipolar or have ADHD added to your other diagnoses, you need to talk with either your primary care Dr. or with a psychiatrist. They will not judge you, but their help is needed to determine if these other problems are present. Each is treated differently, so it's important to get a full evaluation. Once you know what you have, then you can get treatment.