Sexuality is not black and white, and for most people, though it may be something you're born with, it may take years for that person to understand and accept themselves. I've been questioning my sexuality since middle school and by junior year was comfortable with being bisexual, now within this year I realize that I am not bisexual at all but pansexual, which is similar but different.

Your mother doubts you because you're only 14 and have not had the life experiences or have acted on any of those feelings. There's alot about sex and relationships and love you don't understand at your age, it's just life experience. I've gone through bi phases and straight phases and lesbian phases, I even briefly gone through a transgendered phase, all within four years of high school. It takes time, not everyone knows who they are straight from the womb.

And a side comment about society, many people believe that bisexuals are fakes who get drunk and make out for attention. Many people believe that bisexuals are only going through phases, and many people believe that you can't love both guys and girls at the same time. Alot of it is puberty. Everyone questions their sexuality during this time and yes, many people chose to act on it or not. There are straight men who will accept sex from gay men and straight women who will accept sex from gay women. The reasons vary, but alot of it depends on how comfortable a person is with their sexuality.

The most helpful resource for me when I was questioning were finding gay friends and getting involved with a Gay Straight Alliance at my school where they had many LGBT presenters speak and we watched educational videos and went to teen LGBT conventions. Of course, it also helps to explore who you are via dating. And above all else, I was comfortable with my body and my expectations before I would ever give myself to anybody else.

I'm not sure how helpful this is, but you can always PM me and I'll be happy to help.