I think that the first thing to remember is that Wicca is first and foremost a religion. Yes, Wiccans do believe in magic and they do magic every time they cast a circle or charge a ritual tool. But spell casting is a very, very small part of being Wiccan. Many long-time, experienced Wiccans seldom cast spells at all unless there is a very specific need. So there is no need to think of yourself as a "faker" just because you aren't casting spells right now.
It takes time and dedicated study to learn how and why magic works and to master the techniques necessary to be successful at spellcasting. Perhaps you can get your mother and your grandmother to work with you on learning how to do spells. After all, they will be far better teachers than a random stranger that you meet on a message board.
Something else to keep in mind, Wicca is not something that is passed down in the genes, nor for that matter do your genes make you a Witch. Becoming a Wiccan or a Witch is a conscious decision each of us makes and then each of us dedicates our lives to becoming through study and practice. Yes, some people do seem to have more talent than others. But to say one is a Witch or a Wiccan because their ancestors were is like saying someone is a pianist because their parents played the piano. You aren't a pianist until you sit down at the piano and learn how to play.