While researchers are still trying to confirm with a great deal of confidence what causes a person's sexual orientation, one thing more and more are reporting is the fact that one's sexuality can be quite fluid throughout the life cycle. While we're often taught that our sexual orientation is black or white, meaning you're either straight or gay, for plenty of people, their sexual orientation could best be described as in a "gray" zone, with who you're into being explained by where you're at on a continuum of "turn on's".
Works, like Lisa Diamond's book "Sexual Fluidity", share stories of women who, at various points in their lives, find themselves turned onto other women or desiring a relationship with a woman or a particular woman. This could be for any number of reasons, including whether curiosity, finding herself turned off to men, or enjoying a special connection with a specific woman. So what you're experiencing is quite normal for some women. It's nothing to be embarrassed or ashamed about. It's hopefully something you can allow yourself to enjoy more than anything.
All the best,