I was adopted around the time I was three months old by my parents who are both Jewish. I do not know what religion my biological mother was, in fact I have very little detail about her at all. I was raised in a Reform Jewish household, celebrated Jewish holidays, I became a Bar Mitzvah, and always considered myself Jewish.
However, reading many questions on here, for example this one, it's clear that to be Jewish one's mother has to be Jewish. An orthodox friend of mine also said I was not really Jewish, despite the way I was raised.
What is the official view on adoption in the Jewish religion? When I read that my mother must be Jewish for me to be Jewish, does that mean my adoptive mother (the person I have always known as my mother) or my biological mother (a woman I have never met, never knew, and who has no connection to me other than that we share similar DNA and that she carried me for nine months and bore me)?