Recommendation for doctor helping with Low Ferritin

Looking for a recommendation for a hematologist functional medicine doctor that is open to helping with chronic low ferritin without low hemoglobin. I have negative side effects from low ferritin, however, it is difficult to find a doctor that will help with this if your hemoglobin is normal. Does anyone have experience with a doctor that will help in this situation? If not a hematologist, perhaps a good functional medicine doctor who might. Thank you in advance.