Is it needed to get called up to the bimah and, also is it needed for you to lain from the torah on your Bar-Mitzvah?
Jewish law treats a male as an adult as soon as they reach age 13 (assuming they've also had the onset of puberty). There is no official "bar mitzvah" ritual; you're an adult, you're an adult.
It's become normal to demonstrate to everyone that the young man is an adult by calling up the fellow for an aliyah (i.e. saying the brachas before and after the reading), and also usually for reading some or all of the Torah. Or giving him "maftir", so he makes the brachas on the end of the Torah reading, then makes the brachas on the Haftorah (then either he or someone else can read it).
Now it's usually not that hard to prepare for just saying the brachas, and traditional practice is worth a lot, and there is a special bracha that the father makes when his son has his first Aliyah. But again, a boy becomes bar mitzvah no matter what he does.
Rabbi Moshe Rosenberg, rabbi of Etz Chaim in Kew Gardens Hills, suggested in a recent journal article that some boys who aren't really into leining should probably just get an Aliyah, and maybe spend their other bar-mitzva-prep time doing a chessed project.