I have been wondering this myself. When do they stop growing.
Mew must be 15 or 16 weeks old now So my other two oldest are around 12 weeks old. I do know thet have taken a huge growth leap. If Mew sits still long enough, I will snap a shot. She has more coloring then your girl, but some white. I have never had a cat with white coloring. We now have 3. Only Wally so far has only gray as his coloring.