What you may have done is simply used what sexuality was available to you and now have been reinforced, creating a reinforcing cycle. It doesn't necessarily mean you're gay, given your unique circumstances.

But some people are attracted to both sexes (bisexual), and can be turned on by either. This is not something to feel ashamed of, but it does mean your sexuality can be even more confusing because of this. One sign of potentially being bisexual is being turned on by either men or women.

At the end of the day, the only person who can answer these questions for you is yourself. You can second-guess yourself all you want, but underneath all that second-guessing is a set of desires that are honest.