That is the thing about hiding it...You really are NEVER in control of how long it will remain a secret! At any moment you can be found out and the longer you hide it, the more lies you will end up telling and the more people you will end up hurting. In some situations life in the closet may be easier but this is only temporarily. Eventually it can really eat a person up inside.
Being in the closet can also mess up a relationship. Try to imagine if you had a straight friend who had to hide his girlfriend from his parents, friends and the entire world. How long do you think that girl would stick around? Probably not long, especially when there are millions of men in the world who would be proud to be with her and honest about it. No straight couple would want to live this way. So how is it gay people think this will honestly work in the long term? This is something to consider.
You don't have to tell anyone until you are ready. You are still young so chances are, things have been pretty easy to hide up to this point. As you get older things can get more complicated and he longer you wait the harder it can become. Also, NOTHING about you will change unless you want it to. How you act, dress and look is already part of who you are. You are also gay and have been for a long time. The only thing that will change is that people will know. Who you are inside won't change.
Coming out is a big decision and you have to do it when the time is right for you. Only you will know when that is. You have your whole life ahead of you and you deserve to be happy. It sounds like you are being pretty honest with yourself. Now maybe it is time to think about being honest with others. When you do this, you never have to worry about getting caught or about someone finding out. Best of luck!