The fact that "you are different" does not mean a "different you" now exists, though. Change of this specific kind is already intrinsically integrated into your existence and identity.
Change is ssential to human nature. A human exists--and the same human exists--fron fertilization to death. Fertilization is a change before which we can say "not smeej" and after which, "smeej." And death is also a change before which we can say "smeej" and after which, "not smeej." There will be vastly, vastly more cells at death than there were at fertilization (assuming smeej made it out of the womb and to an observable state), and the original fertilized cell will no longer exist, but there is no other point along the existence of smeej in which a change happens of such significance as to alter whether or not the same thing is present.