Amy's food intake dropped a lot at 6 months or so around the time that she got her big girl colours. She is about the same age as Tilly. They actually never stop growing, hence the occasional shedding as adults. Amy shed every month until she got to 6 months, then it slowed right down to every 3 months. Lily used to shed every 3 months also. I haven't noted down exact timing for Tommy, but I think he is about the same.
I love the females' smaller, more rounded body shape! Although Tommy is gorgeous, I just love the little females, they are just so cute! Have you weighed and measured Tilly at all?