Don't judge me, please. I'm a fanfiction reader and I used to read a lot of slash (MxM) fics. They could get me horny and sometimes even get the warm tingly feeling in my stomach. About a week ago, I realized that I might be gay. I've thought about being with women and I'm more comfortable with that idea than being with men. However, when I read femslash (FxF), I don't get very horny. I definitely get a lot of the warm, tingly feelings in my stomach - a lot more than in slash - but the sex scenes don't do a lot for me. If I imagine myself with another woman, that works, but not with fanfiction. And now the slash does nothing for me anymore. What does that mean?
You probably may be bi... But first of all if you have the same feelings for the both genders it means that your bi but if you have more feeling for one of the gender well you may not be bi. To help you try to see yourself dating or having sex with a boy or girl. Maybe there is one that you will feel more confortable with or more attracted. Btw when your questioning your self it can be hard and take some time and it's normal.
In my opinion, I don't feel like reactions to reading something about other characters are clear indicator unless you want it to be. I personally used to read a lot of m/f and m/m fanfic when I was younger and have memories of being turned on but it, but I think it's the sexual act or the connection the characters have rather than self inserting yourself into the situation. We are socialised to know of sex as being an act with men involved, so can react to that more easily sometimes. I also struggled with not being turned on by f/f in writing for a bit and feeling weird reading it despite feeling that I'm likely a lesbian years later. Maybe try finding f/f that is something you genuinely ship a lot, or relate to one of the characters as I find the experience is different. Or see how you feel about reader/female character fic if that makes you comfortable.
