No one can tell you if you are a lesbian. Only YOU can tell. Don't let anyone try to convince you otherwise. There are no "gay quizzes" or tests that can tell for you. I wrote an article about this that may help you:
link
I know, it's really hard to tell. I think it's easier for guys to tell if they are gay because they tend to experiement more. But you don't need to experiment in order to tell, and I wouldn't reccommend sleeping around.
After you find out, you may want to keep it to yourself or come out of the closet to family and friends. But DO NOT do this if your family might kick you out (unless you have a place to go). You might want to get a girlfriend or just stay single for a while. It's all up to you.
Don't try to change yourself. There are no "gay to straight" programs that work, and there never have been. God made you the way He meant to, and He loves you no matter what.