I cannot comment on the recovery time for your child, but can say that each of my children responded on their own timelines for recovery from gluten exposure. We did not have chronic growth issues, but in other areas our recovery has been painfully slow at times. It has taken continual, mindful adherence to strict gluten free protocols.
I believe that making a decision to put a child back on gluten when they respond with painful, systemic symptoms is a decision to make with your healthcare provider - ensure a strategy is in place if the joint decision is to reintroduce gluten. We have utilized standard celiac testing to monitor compliance with gluten free diet and to help evaluate how much to chase other potential, contributing causes. We have found genetic testing helpful in our journey, and it has helped guide our healthcare providers as well. In addition to the celiac testing standards, our pediatric GI specialist also ran some vitamin panels that are commonly deficient in her celiac patients.
I assume you know the importance of remaining gluten free if nursing a gluten free child (but just as important that you remain vigilantly gluten free as a celiac yourself). I am absolutely fascinated by the nursing and celiac relationship. I had a very interesting experience nursing my super sensitive child and wish that there would be further study into the nursing dynamic as it relates to celiac antibody production. I commend you for continuing your nursing relationship.
Another matter to research, consider and discuss with your doctor is the fact that traditional celiac tests like those outlined above are not very accurate for diagnosing the very young. If I recall correctly, getting correct celiac diagnosis in the population under 2 can be very difficult. I also believe that this reality should be seriously considered in evaluating the overall strategy for management and diagnosis of gluten issues in children.
Good luck getting it sorted. Putting together a healthcare team to help you is one of the most important parts of getting things figured out!