A confession to strangers of the internet

I'm a 17 y/o male who, until about a year and a half ago, was exclusively attracted to women. I'm not entirely sure when the "unsureness" began, but I know that I started having sexual feelings for males. I've only briefly thought about a relationship with another male but I decided that I was only romantically attracted to women. In the past, I have gone on chat sites and exchanged "pictures" with other guys my age, but immediately after doing it I felt a sense of guilt for whatever reason. Over the past few days, I have thought more about having sex with women AND men, though I only feel sexual and "dirty" with the guys that I think about and I feel romantically interested in the gals. I've never had sex with either, hell I've never even kissed someone. I'm not exactly sure why I posted this, but it feels really nice to be honest for once. Any advice or comments are appreciated.