Kitten growth

I have a 6 month old spayed female kitten. she seems to have hit a plateau in her growth and I was wondering how much she would still grow from 6 months to a year. Her older brother is large and I thought she'd turn out like him but now I'm having second thoughts. She's about 5 to 7lbs but looks pretty small.Any ideas? what's the normal weight of an adult DSH or is there to great a variance?

There's a variety of sizes and bone structure for cats. Even with cats from the same litters. She will probably grow some between now and 1.5 years and then she will stop.

Thanks!