I've started to notice or accept that I also find Men attractive and I know I should be completely fine with that. I've always been completely fine with bi-sexuality and I understand it. I'm not entirely sure whether I am bi-sexual or not. However, the last couple of weeks it has been flooding my mind and I've got this almost constant sinking feeling in my stomach and I don't know why. I'm just really confused and seeking some advice... sounds stupid I know.
Put it this way. If you are sexually attracted to both males and females, then yes, you are bisexual. As for the sinking feeling, try to ascertain what aspects of your life (whether they be based around your sexual orientation or not) could be causing it. By what you've said, I personally think it's do to with your orientation, despite the fact that you are okay with bisexuality. And no, it doesn't sound stupid. Most of us question at some point. I hope all goes well