My son, age 7, also has a 13 yo BA.  We were told that this means he has now reached about 85% of his adult height. (To do a quick check of your daughter's projected height, based on where she is today, you can, therefore, take her current height and divide by 0.85. E.g. if she is 54" tall today, with a 13yo BA, her predicted height would be around 63.5")

We were also told that most of adult height is reached by about BA 15 1/2, though growth does not completely stop till around BA 17.  These are based on statistical averages, though, and each child may reach these milestones at slightly different times.

As Beth mentioned, Lupron is often prescribed for precocious puberty.  It therefore slows down BA advancement, giving the child more time to grow.  Was your daughter treated with that, as well?