How much more will she grow?

["guest@endurance.net" <guest@endurance.net>]

Judy JudyK89@aol.com
I'm thinking of trading my mare (the one that ties up)for another
mare the owner has, but she's only 2 12 years old.  I like her,
she seems very sweet and calm, but she also seems very small and
 dainty. I don't have much experience with baby's, how much more
 will she grow?  Will her legs (the bones) get thicker?  I know
 exercise will help tendons and bones, but that won't be until I
 can start riding (which won't be for quite a while).  How do I
 know if this mare will grow into the size I need?  Or is there
 no way of knowing?