Wow, our 11 year old daughters sound very similar with their bone age delay! I definitely would encourage you to ask for a DEXA scan to check her bone density. We have been convinced by multiple doctors that it is very important to address her low bone density before she starts that big pre-pubertal growth spurt. I am also not at all upset by the delay in puberty (I have a 14-next-week daughter, too), and actually my daughter isn't either. She sees what her sister has dealt with and isn't in any hurry, plus she's a ballerina so likes being small and thin. Her doctors also say that she should be able to make up the delay in growth, and if she does what they predict, she has about 12 or 13 inches to grow in the next few years. Her bone density is extremely low, so we really worry about her spine as she grows that fast.
Where do you live? We're in the Shenandoah Valley of Virginia. I know my daughter would love to have a gluten-free friend with similar issues!