"I have been attracted to Judaism ever since I first began to learn about it, and have reason to believe that my family was originally Jewish. What would be the steps for me to take to return to Judaism?"
Discovering or rediscovering one's personal history and family history can be a profoundly enriching and transforming experience.
Conversion to Judaism is a process of cognitive and affective development - that is, learning what it means and how to be Jewish and then experiencing and internalizing what has been learned. While a conversion ceremony is transforming in several ways it is also a statement that the celebrant has become Jewish and is ready to declare their Jewish identity and commitment.
You have obviously done a great deal of work and searching to this point. This process cannot, however, been done alone. It requires a rabbi as a guide and a congregation as the full context. Your next step should be to contact the rabbi of the local Reform congregation. Find a synagogue near you.