I had my Bar Mitzvah before I was thirteen and I read a different Parsha than the one for my actual Hebrew Birthday. Do I have to do it again? I’m now 17.
Don’t worry! Everything’s ok.
A Jewish boy becomes a Bar Mitzvah on the Hebrew date of his thirteenth birthday (as a girl becomes a bas mitzvah on her twelfth). This means you become obligated in all the laws of the Torah like an adult on this day. This happens automatically, ceremony or no ceremony. It’s become somewhat of a tradition to celebrate this occasion and for a boy to be called up to the Torah (or even to read from the Torah) the first Shabbos after his birthday since this is the first time in his life that he is entitled to do so. But this tradition only enhances the occasion; the occasion occurs either way.
While you did celebrate your bar mitzvah early, there’s no prohibition against making a party whenever you want. Even though you were probably called up to the Torah before your Bar Mitzvah, which is not the Ashkenazi custom, this is not necessarily a problem either. Sefardic Jews have the custom to call older children (but under Bar Mitzvah) up to the Torah, so you can rely on their tradition to comfort you so long after the fact. Plus, you may even be Sefardic, in which case there wouldn’t be any issue at all. Plus, everyone agrees that an older child can be called up for the Haftorah. Plus (and this is perhaps the most important point), you are not responsible for any of this since you were under bar mitzvah at the time!
So relax. You are 100% a Bar Mitzvah, like every Jewish boy over thirteen years old (or girl over twelve). Enjoy your G-d given right and responsibility! It’s the greatest gift (and Bar Mitzvah present) in the world.
Much success and take care.
Shlomo Shulman