Think about it.
No, honestly. Only you can know exactly how you feel so only you can ever know who you are, who you find attractive, who you would want to be in a relationship with. But it's not like it is absolutely obvious as soon as you start questioning. It takes time. Read about different options and what others say about how they feel and just think about how much that feels right for you. It might also help to just go with one option for a while and see if it feels right. That doesn't mean you have to come out to everyone immediately. Just define it for yourself at first and if at some point you realize it isn't what you want try a different one. The biggest step is starting to ask yourself. Not just accepting what's "normal" but actually thinking about who you are. Everything else will fall into place eventually. It might not be this month, it might not be this year, it most certainly will not be today... but at some point you will feel it.