>>1 It stinks that your mom just brushed it off like that, I imagine it could be pretty hurtful if someone just trivialized it like that. But just know that you're the only one who can define yourself, and if you say you're not confused then, well. That's that. However old you are, you can know your own sexuality and accept any label you feel is right for you. Still, it's totally okay to have doubts and all... I actually came out to my friends more than once. Because over time, I kept discovering more about myself and realized that I identified with this sexuality rather than that one, and all that stuff.
In time things will become clearer. And like
>>2 said, it'll get better too.