Bobby,
Yes I might suspect you have the wrong plant if it gets very large. Here in OR the conditions for growth are optimal and it never gets to that size nor did it for me in MA. With the arachnoideum 'Tomentosum' as the pod parent it should be quite small. The biggest I have ever seen it is ~4" and that was a plant that would flower that season. I do have rosettes ~10" across in several of my seedlings so I know the plants are growing close to optimally.
Kevin
