Sometimes stress can delay your period or cause you to not have it at all. You really should take a pregnancy test. That way if you are not pregnant you can stop stressing about. The possibilities are slim, but if you are then you can start planning. You really should take this scare as a sign that you are not ready to be having sex. I am not sure if your parents have talked to you about sex, but it is a big responsibility and you have a lot of things at stake like your emotions.
Look at it this way, if your future spouse was to see you now would he approve of what you are doing. I wish someone would have told me that when i was younger. Make good choices now because you will have to live with them for the rest of your life (I wish some one would have told me that too). Good luck