Lovely, very nice Corn.
i hope you dont mind but i would suggest incresing the amount of food you give her or up the size of mice you are giving.
I know their could be alsorts of reasons why she is so small at two years.
Try giving her a small mouse every week for 4 weeks then up it to two for 4 months then up it again.
with any luck you should see a big improvement in her size after 6 months.
she definatly looks like she can handle more mice of a larger size.
Paul.