If your online voice and your real voice have never met, one of them is lying.

Running two versions of yourself costs more than either one is worth. If the person in your posts is meaner, funnier, more confident or more polished than the person who shows up at school, you are maintaining a character, and characters are exhausting to keep consistent. Somebody eventually meets both and notices the seam.

Read your last ten posts as though a person who knows you well is reading over your shoulder. Anything that makes you flinch is the gap. Move one of the two voices toward the other, and let it be the honest one.