For me, I believed I was hetero, because that was how I was taught to behave. That created a lot of internal issues that resulted in three failed marriages and numerous other hetero relationships. In therapy, my psychologist helped me find the root of the problem. I am not hetero, I am asexual. He said that it had nothing to do with being transgender, except that trying to behave in a hetero manner was causing dysphoria.
Now I understand and have come to accept myself as asexual, transfeminine.