Orthodox Conversion Without Being Orthodox

I was raised by my father and stepmother, who to me is my mother. My father and stepmother are both Jewish. My biological mother was not Jewish. All my siblings who are the flesh and blood of my stepmother are Jewish and one of them became religious. And the woman I want to marry is Jewish. I was raised fully as a Jew with no hint of any other religion, and I had a bar mitzvah. Everyone who knows me thinks I am Jewish. But Jewish law doesn’t consider me Jewish because my biological mother who died when I was an infant was not. I can easily have a Reformed or Conservative conversion, but I want one that is Orthodox. I want to be just like everyone in my family and community. Is there any way, any loophole, where I can have an orthodox conversion to Judaism but not be fully observant and still be myself thereafter?