Honestly, from what I am aware of, there isn't really a mini rott. Betti is about the same size as your pup and I don't consider her to be a mini rott. She's shorter and compact, yes, compared to many rotties I see in public, but she is very well formed and cute as a bug. I am aware that she was the runt and both of her parents are a bit bigger than her, but they are larger structurally and not necessarily height-wise. I wouldn't worry one bit about your girl. In fact, it may be better that she is not tall and gangly because it may be beneficial to her joints to support less weight on a stouter frame. Betti is extremely structurally sound.