Hello and welcome to the EA
I am only 22, so not much older than you.
Unfortunately sexual orientation is probably not changeable in most cases, although neither way has been conclusively proven.
I would definitely recommend that you speak with a professional counselor who has experience with gender and sexuality issues. This could be a much bigger help to you than you think. It could help you not only discover who you are, but maybe even grow to accept it and become comfortable with it as well.
Sexual orientation really is much less simple than just gay or straight. Most of the population has some degree of attraction to both men and women, even though most men in particular would never admit it.
Do you have any type of fantasies about women? Do their bodies appeal to you sexually at all? If so, then which do you fantasize about more often, men or women? If not, then you may very well be one of those very few with an exclusive attraction to only men.
Regardless of where you fall, you probably cannot change it, so a good first step would be to accept that fact. A professional can help you with that acceptance if you cannot do it on your own.
Now, there are some gay men who simply cannot accept their sexuality regardless of how much help they get, and they certainly have the right to feel that way. A few of those have turned to castration to eliminate gay sexual thoughts. While castration would probably eliminate or at least significantly reduce your fantasies about guys, I would under no circumstances recommend that you even consider it until you first discover who you are and see if you can bring yourself to accept it. You do not mention castration in this post, but since you are here chances are it has crossed your mind. Castration is a very extreme measure and should only be undergone as a last resort, especially when its purpose is to eliminate a sexuality you are not comfortable with.
Hope I gave you some things to think about, and I would be glad to chat further if you would like to
