No joke about feeding rats. After jojo got his first rat he started a shed cycle the next day. Length and weight strongly depends on feeding the appropriate size prey item. But like people ball pythons come in all shapes and sizes. If you notice that sheds are coming regularly then he is right on schedule as far a growth. But remember these guys can stretch themselves out and make themselves look longer and they can scrunch up and make themselves look shorter. The best way is not to measure them but to weight them. Jojo had a tick not too long ago and i weigh him every sunday before i feed him. I noticed that he was losing weight. After the tick was removed he gained back some so weight is IMO the best way to judge growth.