The answer to your question is yes, bipolar disorder or chemical depression can go unnoticed or not diagnosed for years. If a person has been under psychiatric care then it would be detected by the doctor and further investigation would be done to make the diagnosis and then treatment begins. Some people go through life having a difficult time with themselves, as well as dealing with others, and develop low self esteem, but don't seek help. However once the person realizes that something is wrong and goes to the doctor for help, they can begin to work things out and feel better. Usually psychological or psychiatric counseling along with medication therapy such as antidepressants, helps tremendously.
Thank you very much for the extra added detail. I can hear you loud and clear and I think you are ready to be helped. I strongly recommend individual or group therapy for you so you can start revealing what you have been through, and seek support and help from others. You may feel that you did not have the best time growing up, but that does not mean that you have bipolar disorder. As a matter of fact the symptoms that you describe don't sound like those of BD. Talking with a mental health professional should help you tremendously. It sounds like you need to move on from your past and look ahead to a bright future. You can call the local hospital and ask if they have any ongoing therapy groups and find out who runs them. You do eventually need to be under the care of a psychiatrist, who will determine the cause of your problem and he can provide proper medication for you. However you will still benefit from a therapy group.
I wish you well!
The symptoms that you describe are not particular to asperger's disorder. You write and express yourself very well. I recognize that you have been through situations that you did not desire as a child and I feel like you are trying to find that something is wrong with you so that you can fix it. You can begin getting healthy right now. You need a very good therapist to talk to so that you can work through your problems, past and present. You really sound like a wonderful person and I think you deserve the best. Instead of looking for things wrong in your life, I suggest moving forward by helping yourself to heal. You can do this with therapy and medication, if prescribed. Try to start by writing down all of the good things about yourself and any good memories that you have.