Coming out to my parents

My mother has told me before that being bisexual means you've had sexual intercourse with a woman. I'm a virgin and I find bother genders attractive, I'm open to dating either and well. My mother has also told me that she will be happy with anything that I come out to her as. What do I do? I'm openly bisexual to anyone that asks except my parents... :/ I'm afraid to tell them and I've been hiding it from them for almost a year now. Any advice?