How do I do I date girls when I'm in the closet?

I am a sixteen year old bisexual girl who is a Junior in high school. Is it normal to try to hide it:/? My close friends know, but that's about it. I've been asked out by girls before, but I declined because I am afraid people would find out. Sometimes I fantasize about moving up to San Fransisco for college and settling down with a woman later on, adopting a baby when we get older. I know it sounds silly. I really do like men, but I get along better with woman, although I like men's bodies better. Does this sound stupid? Agh. How do I date girls without other people knowing? My friends are more than okay with it,happy even. My Mom is embaressed of it and says that God is unhappy with my liking girls. My brother just says that it would be better to come out of the closet Senior year or in college, when people are more accepting. (only my brother and Mom know in my family)